diff --git a/browser/modules/test/unit/test_E10SUtils_nested_URIs.js b/browser/modules/test/unit/test_E10SUtils_nested_URIs.js
index 4d2205c8519b..8fe4528fad55 100644
--- a/browser/modules/test/unit/test_E10SUtils_nested_URIs.js
+++ b/browser/modules/test/unit/test_E10SUtils_nested_URIs.js
@@ -5,7 +5,6 @@ const { E10SUtils } = ChromeUtils.importESModule(
 var TEST_PREFERRED_REMOTE_TYPES = [
   E10SUtils.WEB_REMOTE_TYPE,
   E10SUtils.NOT_REMOTE,
-  "fakeRemoteType",
 ];
 
 var TEST_USE_REMOTE_SUBFRAMES = [true, false];
diff --git a/caps/nsScriptSecurityManager.cpp b/caps/nsScriptSecurityManager.cpp
index aaca13e98a07..ddeb7ec7d138 100644
--- a/caps/nsScriptSecurityManager.cpp
+++ b/caps/nsScriptSecurityManager.cpp
@@ -1073,7 +1073,7 @@ nsresult nsScriptSecurityManager::CheckLoadURIFlags(
         }
 
         auto& remoteType = dom::ContentChild::GetSingleton()->GetRemoteType();
-        if (remoteType == PRIVILEGEDABOUT_REMOTE_TYPE) {
+        if (remoteType.IsPrivilegedAbout()) {
           return NS_OK;
         }
       }
diff --git a/docshell/base/BrowsingContext.cpp b/docshell/base/BrowsingContext.cpp
index 783bbea83fca..a77e8cc62c0a 100644
--- a/docshell/base/BrowsingContext.cpp
+++ b/docshell/base/BrowsingContext.cpp
@@ -1655,8 +1655,7 @@ bool BrowsingContext::CrossOriginIsolated() {
              nsILoadInfo::
                  OPENER_POLICY_SAME_ORIGIN_EMBEDDER_POLICY_REQUIRE_CORP &&
          XRE_IsContentProcess() &&
-         StringBeginsWith(ContentChild::GetSingleton()->GetRemoteType(),
-                          WITH_COOP_COEP_REMOTE_TYPE_PREFIX);
+         ContentChild::GetSingleton()->GetRemoteType().IsWebCoopCoep();
 }
 
 void BrowsingContext::SetTriggeringAndInheritPrincipals(
diff --git a/docshell/base/BrowsingContextGroup.cpp b/docshell/base/BrowsingContextGroup.cpp
index 30f153be7ceb..ca68cdc7e9e7 100644
--- a/docshell/base/BrowsingContextGroup.cpp
+++ b/docshell/base/BrowsingContextGroup.cpp
@@ -131,10 +131,12 @@ void BrowsingContextGroup::EnsureHostProcess(ContentParent* aProcess) {
   MOZ_DIAGNOSTIC_ASSERT(!mDestroyed);
   MOZ_DIAGNOSTIC_ASSERT(this != sChromeGroup,
                         "cannot have content host for chrome group");
-  MOZ_DIAGNOSTIC_ASSERT(aProcess->GetRemoteType() != PREALLOC_REMOTE_TYPE,
-                        "cannot use preallocated process as host");
-  MOZ_DIAGNOSTIC_ASSERT(!aProcess->GetRemoteType().IsEmpty(),
+  MOZ_DIAGNOSTIC_ASSERT(aProcess->GetRemoteType().IsKnown(),
                         "host process must have remote type");
+  MOZ_DIAGNOSTIC_ASSERT(!aProcess->GetRemoteType().IsPrealloc(),
+                        "cannot use preallocated process as host");
+  MOZ_DIAGNOSTIC_ASSERT(!aProcess->GetRemoteType().IsNotRemote(),
+                        "host process must be remote");
 
   // XXX: The diagnostic crashes in bug 1816025 seemed to come through caller
   // ContentParent::GetNewOrUsedLaunchingBrowserProcess where we already
@@ -168,7 +170,7 @@ void BrowsingContextGroup::EnsureHostProcess(ContentParent* aProcess) {
 
 void BrowsingContextGroup::RemoveHostProcess(ContentParent* aProcess) {
   MOZ_DIAGNOSTIC_ASSERT(aProcess);
-  MOZ_DIAGNOSTIC_ASSERT(aProcess->GetRemoteType() != PREALLOC_REMOTE_TYPE);
+  MOZ_DIAGNOSTIC_ASSERT(!aProcess->GetRemoteType().IsPrealloc());
   auto entry = mHosts.Lookup(aProcess->GetRemoteType());
   if (entry && entry.Data() == aProcess) {
     entry.Remove();
@@ -193,7 +195,7 @@ static void CollectContextInitializers(
 void BrowsingContextGroup::Subscribe(ContentParent* aProcess) {
   MOZ_DIAGNOSTIC_ASSERT(!mDestroyed);
   MOZ_DIAGNOSTIC_ASSERT(aProcess && !aProcess->IsLaunching());
-  MOZ_DIAGNOSTIC_ASSERT(aProcess->GetRemoteType() != PREALLOC_REMOTE_TYPE);
+  MOZ_DIAGNOSTIC_ASSERT(!aProcess->GetRemoteType().IsPrealloc());
 
   // Check if we're already subscribed to this process.
   if (!mSubscribers.EnsureInserted(aProcess)) {
@@ -235,7 +237,7 @@ void BrowsingContextGroup::Subscribe(ContentParent* aProcess) {
 
 void BrowsingContextGroup::Unsubscribe(ContentParent* aProcess) {
   MOZ_DIAGNOSTIC_ASSERT(aProcess);
-  MOZ_DIAGNOSTIC_ASSERT(aProcess->GetRemoteType() != PREALLOC_REMOTE_TYPE);
+  MOZ_DIAGNOSTIC_ASSERT(!aProcess->GetRemoteType().IsPrealloc());
   mSubscribers.Remove(aProcess);
   aProcess->RemoveBrowsingContextGroup(this);
 
@@ -247,7 +249,7 @@ void BrowsingContextGroup::Unsubscribe(ContentParent* aProcess) {
 }
 
 ContentParent* BrowsingContextGroup::GetHostProcess(
-    const nsACString& aRemoteType) {
+    const RemoteType& aRemoteType) {
   return mHosts.GetWeak(aRemoteType);
 }
 
diff --git a/docshell/base/BrowsingContextGroup.h b/docshell/base/BrowsingContextGroup.h
index 34027c390db8..f3e15959deb6 100644
--- a/docshell/base/BrowsingContextGroup.h
+++ b/docshell/base/BrowsingContextGroup.h
@@ -7,6 +7,7 @@
 
 #include "mozilla/PrincipalHashKey.h"
 #include "mozilla/dom/BrowsingContext.h"
+#include "mozilla/dom/RemoteType.h"
 #include "nsRefPtrHashtable.h"
 #include "nsHashKeys.h"
 #include "nsTArray.h"
@@ -82,7 +83,7 @@ class BrowsingContextGroup final : public nsWrapperCache {
   // Look up the process which should be used to host documents with this
   // RemoteType. This will be a non-dead process associated with this
   // BrowsingContextGroup, if possible.
-  ContentParent* GetHostProcess(const nsACString& aRemoteType);
+  ContentParent* GetHostProcess(const RemoteType& aRemoteType);
 
   // Check if the process which sent the message being read from aReader is
   // aware of this BrowsingContextGroup's existence.
@@ -297,7 +298,7 @@ class BrowsingContextGroup final : public nsWrapperCache {
   // A non-launching host process must also be a subscriber, though a launching
   // host process may not yet be subscribed, and a subscriber need not be a host
   // process.
-  nsRefPtrHashtable<nsCStringHashKey, ContentParent> mHosts;
+  nsRefPtrHashtable<nsGenericHashKey<RemoteType>, ContentParent> mHosts;
 
   // Whether or not a given http(s) origin uses origin or siteOrigin-keyed
   // DocGroups/AgentClusters. Only contains entries for http(s) origins.
diff --git a/docshell/base/CanonicalBrowsingContext.cpp b/docshell/base/CanonicalBrowsingContext.cpp
index 1fa976de8af7..bfe3f437bf83 100644
--- a/docshell/base/CanonicalBrowsingContext.cpp
+++ b/docshell/base/CanonicalBrowsingContext.cpp
@@ -247,7 +247,7 @@ void CanonicalBrowsingContext::GetCurrentRemoteType(nsACString& aRemoteType,
                                                     ErrorResult& aRv) const {
   // If we're in the parent process, dump out the void string.
   if (mProcessId == 0) {
-    aRemoteType = NOT_REMOTE_TYPE;
+    aRemoteType = RemoteType::NotRemote().Stringify();
     return;
   }
 
@@ -257,7 +257,7 @@ void CanonicalBrowsingContext::GetCurrentRemoteType(nsACString& aRemoteType,
     return;
   }
 
-  aRemoteType = cp->GetRemoteType();
+  aRemoteType = cp->GetRemoteType().Stringify();
 }
 
 void CanonicalBrowsingContext::SetOwnerProcessId(uint64_t aProcessId) {
@@ -2546,7 +2546,8 @@ CanonicalBrowsingContext::ChangeRemoteness(
     return RemotenessPromise::CreateAndReject(NS_ERROR_NOT_AVAILABLE, __func__);
   }
 
-  if (aOptions.mRemoteType.IsEmpty() && (!IsTop() || !GetEmbedderElement())) {
+  if (aOptions.mRemoteType.IsNotRemote() &&
+      (!IsTop() || !GetEmbedderElement())) {
     NS_WARNING("Cannot load non-remote subframes");
     return RemotenessPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
   }
@@ -2615,7 +2616,8 @@ CanonicalBrowsingContext::ChangeRemoteness(
         "which will never perform a process-switch to being in-process with "
         "their embedder");
     MOZ_DIAGNOSTIC_ASSERT(!aOptions.mReplaceBrowsingContext);
-    MOZ_DIAGNOSTIC_ASSERT(!aOptions.mRemoteType.IsEmpty());
+    MOZ_DIAGNOSTIC_ASSERT(aOptions.mRemoteType.IsKnown());
+    MOZ_DIAGNOSTIC_ASSERT(!aOptions.mRemoteType.IsNotRemote());
     MOZ_DIAGNOSTIC_ASSERT(!change->mWaitingForPrepareToChange);
     MOZ_DIAGNOSTIC_ASSERT(!change->mSpecificGroup);
 
@@ -2628,7 +2630,7 @@ CanonicalBrowsingContext::ChangeRemoteness(
   }
 
   // Switching to the parent process.
-  if (aOptions.mRemoteType.IsEmpty()) {
+  if (aOptions.mRemoteType.IsNotRemote()) {
     change->ProcessLaunched();
     return promise.forget();
   }
@@ -3631,7 +3633,7 @@ void CanonicalBrowsingContext::RemovePageAwakeRequest() {
 }
 
 void CanonicalBrowsingContext::CloneDocumentTreeInto(
-    CanonicalBrowsingContext* aSource, const nsACString& aRemoteType,
+    CanonicalBrowsingContext* aSource, const RemoteType& aRemoteType,
     embedding::PrintData&& aPrintData) {
   NavigationIsolationOptions options;
   options.mRemoteType = aRemoteType;
diff --git a/docshell/base/CanonicalBrowsingContext.h b/docshell/base/CanonicalBrowsingContext.h
index 7a5b8c85d14a..484dadb86f39 100644
--- a/docshell/base/CanonicalBrowsingContext.h
+++ b/docshell/base/CanonicalBrowsingContext.h
@@ -269,8 +269,9 @@ class CanonicalBrowsingContext final : public BrowsingContext {
   // The returned CanonicalBrowsingContext may be different than |this| if a BCG
   // switch was performed.
   //
-  // A NOT_REMOTE_TYPE aRemoteType argument will perform a process switch into
-  // the parent process, and the method will resolve with a null BrowserParent.
+  // A RemoteType::NotRemote() aRemoteType argument will perform a process
+  // switch into the parent process, and the method will resolve with a null
+  // BrowserParent.
   using RemotenessPromise = MozPromise<
       std::pair<RefPtr<BrowserParent>, RefPtr<CanonicalBrowsingContext>>,
       nsresult, false>;
@@ -445,7 +446,7 @@ class CanonicalBrowsingContext final : public BrowsingContext {
 
   MOZ_CAN_RUN_SCRIPT
   void CloneDocumentTreeInto(CanonicalBrowsingContext* aSource,
-                             const nsACString& aRemoteType,
+                             const RemoteType& aRemoteType,
                              embedding::PrintData&& aPrintData);
 
   // Returns a Promise which resolves when cloning documents for printing
diff --git a/docshell/base/nsAboutRedirector.cpp b/docshell/base/nsAboutRedirector.cpp
index 239b0600b6da..1ec396c84c3e 100644
--- a/docshell/base/nsAboutRedirector.cpp
+++ b/docshell/base/nsAboutRedirector.cpp
@@ -60,7 +60,7 @@ class CrashChannel final : public nsBaseChannel {
       using ContentParent = mozilla::dom::ContentParent;
       nsTArray<RefPtr<ContentParent>> toKill;
       for (auto* cp : ContentParent::AllProcesses(ContentParent::eLive)) {
-        if (cp->GetRemoteType() == EXTENSION_REMOTE_TYPE) {
+        if (cp->GetRemoteType().IsExtension()) {
           toKill.AppendElement(cp);
         }
       }
diff --git a/docshell/base/nsDocShellLoadState.cpp b/docshell/base/nsDocShellLoadState.cpp
index 81bd3323e022..6587442daf58 100644
--- a/docshell/base/nsDocShellLoadState.cpp
+++ b/docshell/base/nsDocShellLoadState.cpp
@@ -51,8 +51,8 @@ using namespace mozilla::dom;
 static mozilla::StaticRefPtr<nsIURIFixup> sURIFixup;
 
 static bool ContentTriggeredURILoadIsAllowed(
-    nsIURI* aURI, const nsACString& aEffectiveRemoteType) {
-  MOZ_ASSERT(aEffectiveRemoteType != NOT_REMOTE_TYPE);
+    nsIURI* aURI, const RemoteType& aEffectiveRemoteType) {
+  MOZ_ASSERT(!aEffectiveRemoteType.IsNotRemote());
   MOZ_ASSERT(!aURI->SchemeIs("javascript"), "Should have been blocked already");
 
   // view-source: URIs are not linkable from web content, but the "View Page
@@ -232,7 +232,7 @@ nsDocShellLoadState::nsDocShellLoadState(
       }
     }
 
-    if (mTriggeringRemoteType != NOT_REMOTE_TYPE) {
+    if (!mTriggeringRemoteType.IsNotRemote()) {
       if (mURI->SchemeIs("javascript")) {
         aActor->FatalError("Illegal cross-process javascript: load attempt");
         return;
@@ -244,8 +244,8 @@ nsDocShellLoadState::nsDocShellLoadState(
       }
     }
 
-    const nsCString& effectiveRemoteType = GetEffectiveTriggeringRemoteType();
-    if (effectiveRemoteType != NOT_REMOTE_TYPE &&
+    const RemoteType& effectiveRemoteType = GetEffectiveTriggeringRemoteType();
+    if (!effectiveRemoteType.IsNotRemote() &&
         !ContentTriggeredURILoadIsAllowed(mURI, effectiveRemoteType)) {
       nsAutoCString aboutModuleOrScheme;
       if (mURI->SchemeIs("about")) {
@@ -255,10 +255,10 @@ nsDocShellLoadState::nsDocShellLoadState(
         mURI->GetScheme(aboutModuleOrScheme);
         aboutModuleOrScheme.AppendLiteral(":");
       }
-      nsCString remotePrefix(RemoteTypePrefix(effectiveRemoteType));
       aActor->FatalError(
           nsPrintfCString("Illegal load attempt of %s URL from %s",
-                          aboutModuleOrScheme.get(), remotePrefix.get())
+                          aboutModuleOrScheme.get(),
+                          effectiveRemoteType.StringifyKind().get())
               .get());
       return;
     }
@@ -401,7 +401,7 @@ nsDocShellLoadState::nsDocShellLoadState(nsIURI* aURI, uint64_t aLoadIdentifier)
       mWasCreatedRemotely(false),
       mTriggeringRemoteType(XRE_IsContentProcess()
                                 ? ContentChild::GetSingleton()->GetRemoteType()
-                                : NOT_REMOTE_TYPE),
+                                : RemoteType::NotRemote()),
       mSchemelessInput(nsILoadInfo::SchemelessInputTypeUnset),
       mIsInitialAboutBlankHandlingProhibited(false) {
   MOZ_ASSERT(aURI, "Cannot create a LoadState with a null URI!");
@@ -650,19 +650,31 @@ nsresult nsDocShellLoadState::CreateFromLoadURIOptions(
   }
 
   if (aLoadURIOptions.mTriggeringRemoteType.WasPassed()) {
+    RemoteType triggeringRemoteType =
+        RemoteType::Parse(aLoadURIOptions.mTriggeringRemoteType.Value());
+    if (!triggeringRemoteType) {
+      NS_WARNING("Invalid TriggeringRemoteType from LoadURIOptions");
+      return NS_ERROR_INVALID_ARG;
+    }
+
     if (XRE_IsParentProcess()) {
-      loadState->SetTriggeringRemoteType(
-          aLoadURIOptions.mTriggeringRemoteType.Value());
+      loadState->SetTriggeringRemoteType(triggeringRemoteType);
     } else if (ContentChild::GetSingleton()->GetRemoteType() !=
-               aLoadURIOptions.mTriggeringRemoteType.Value()) {
+               triggeringRemoteType) {
       NS_WARNING("Invalid TriggeringRemoteType from LoadURIOptions in content");
       return NS_ERROR_INVALID_ARG;
     }
   }
 
   if (aLoadURIOptions.mRemoteTypeOverride.WasPassed()) {
-    loadState->SetRemoteTypeOverride(
-        aLoadURIOptions.mRemoteTypeOverride.Value());
+    RemoteType remoteTypeOverride =
+        RemoteType::Parse(aLoadURIOptions.mRemoteTypeOverride.Value());
+    if (!remoteTypeOverride) {
+      NS_WARNING("Invalid RemoteTypeOverride from LoadURIOptions");
+      return NS_ERROR_INVALID_ARG;
+    }
+
+    loadState->SetRemoteTypeOverride(remoteTypeOverride);
   }
 
   loadState->SetSchemelessInput(static_cast<nsILoadInfo::SchemelessInputType>(
@@ -1203,27 +1215,28 @@ nsDocShellLoadState::TakeSpeculativeListener() {
 }
 
 void nsDocShellLoadState::SetRemoteTypeOverride(
-    const nsCString& aRemoteTypeOverride) {
+    const RemoteType& aRemoteTypeOverride) {
   MOZ_DIAGNOSTIC_ASSERT(
       NS_IsAboutBlank(mURI),
       "Should only have aRemoteTypeOverride for about:blank URIs");
   mRemoteTypeOverride = mozilla::Some(aRemoteTypeOverride);
 }
 
-const nsCString& nsDocShellLoadState::GetEffectiveTriggeringRemoteType() const {
+const RemoteType& nsDocShellLoadState::GetEffectiveTriggeringRemoteType()
+    const {
   // Consider non-errorpage loads from session history as being triggred by the
   // parent process, as we'll validate them against the history entry.
   //
   // NOTE: Keep this check in-sync with the session-history validation check in
   // `DocumentLoadListener::Open`!
   if (LoadIsFromSessionHistory() && LoadType() != LOAD_ERROR_PAGE) {
-    return NOT_REMOTE_TYPE;
+    return RemoteType::NotRemote();
   }
   return mTriggeringRemoteType;
 }
 
 void nsDocShellLoadState::SetTriggeringRemoteType(
-    const nsACString& aTriggeringRemoteType) {
+    const RemoteType& aTriggeringRemoteType) {
   MOZ_DIAGNOSTIC_ASSERT(XRE_IsParentProcess(), "only settable in parent");
   mTriggeringRemoteType = aTriggeringRemoteType;
 }
@@ -1236,7 +1249,7 @@ void nsDocShellLoadState::AssertProcessCouldTriggerLoadIfSystem() {
   // nsContentSecurityManager checks, however this assertion should happen
   // closer to whichever caller is triggering the system-principal load.
   if (TriggeringPrincipal()->IsSystemPrincipal() &&
-      mozilla::dom::IsWebRemoteType(GetEffectiveTriggeringRemoteType())) {
+      GetEffectiveTriggeringRemoteType().IsWeb()) {
     bool localFile = false;
     if (NS_SUCCEEDED(NS_URIChainHasFlags(
             URI(), nsIProtocolHandler::URI_IS_LOCAL_FILE, &localFile)) &&
diff --git a/docshell/base/nsDocShellLoadState.h b/docshell/base/nsDocShellLoadState.h
index 8dd38a5c14d7..21ac1f05f338 100644
--- a/docshell/base/nsDocShellLoadState.h
+++ b/docshell/base/nsDocShellLoadState.h
@@ -7,6 +7,7 @@
 
 #include "mozilla/dom/BrowsingContext.h"
 #include "mozilla/dom/NavigationBinding.h"
+#include "mozilla/dom/RemoteType.h"
 #include "mozilla/dom/SessionHistoryEntry.h"
 #include "mozilla/dom/UserNavigationInvolvement.h"
 #include "mozilla/dom/LoadURIOptionsBinding.h"
@@ -363,11 +364,13 @@ class nsDocShellLoadState final {
 
   bool IsMetaRefresh() const { return mIsMetaRefresh; }
 
-  const mozilla::Maybe<nsCString>& GetRemoteTypeOverride() const {
+  const mozilla::Maybe<mozilla::dom::RemoteType>& GetRemoteTypeOverride()
+      const {
     return mRemoteTypeOverride;
   }
 
-  void SetRemoteTypeOverride(const nsCString& aRemoteTypeOverride);
+  void SetRemoteTypeOverride(
+      const mozilla::dom::RemoteType& aRemoteTypeOverride);
 
   void SetSchemelessInput(nsILoadInfo::SchemelessInputType aSchemelessInput) {
     mSchemelessInput = aSchemelessInput;
@@ -402,9 +405,10 @@ class nsDocShellLoadState final {
   // originally, however non-errorpage history loads are always considered to be
   // triggered by the parent process, as we can validate them against the
   // history entry.
-  const nsCString& GetEffectiveTriggeringRemoteType() const;
+  const mozilla::dom::RemoteType& GetEffectiveTriggeringRemoteType() const;
 
-  void SetTriggeringRemoteType(const nsACString& aTriggeringRemoteType);
+  void SetTriggeringRemoteType(
+      const mozilla::dom::RemoteType& aTriggeringRemoteType);
 
   // Diagnostic assert if this is a system-principal triggered load, and it is
   // trivial to determine that the effective triggering remote type would not be
@@ -758,10 +762,10 @@ class nsDocShellLoadState final {
   nsCOMPtr<nsIURI> mUnstrippedURI;
 
   // If set, the remote type which the load should be completed within.
-  mozilla::Maybe<nsCString> mRemoteTypeOverride;
+  mozilla::Maybe<mozilla::dom::RemoteType> mRemoteTypeOverride;
 
   // Remote type of the process which originally requested the load.
-  nsCString mTriggeringRemoteType;
+  mozilla::dom::RemoteType mTriggeringRemoteType;
 
   // if the address had an intentional protocol
   nsILoadInfo::SchemelessInputType mSchemelessInput =
diff --git a/dom/base/ChromeUtils.cpp b/dom/base/ChromeUtils.cpp
index dac837e73302..038c43a873c5 100644
--- a/dom/base/ChromeUtils.cpp
+++ b/dom/base/ChromeUtils.cpp
@@ -2062,44 +2062,44 @@ already_AddRefed<Promise> ChromeUtils::RequestProcInfo(GlobalObject& aGlobal,
     // Convert the remoteType into a ProcType.
     // Ideally, the remoteType should be strongly typed
     // upstream, this would make the conversion less brittle.
-    const nsAutoCString remoteType(contentParent->GetRemoteType());
-    if (StringBeginsWith(remoteType, FISSION_WEB_REMOTE_TYPE)) {
-      // WARNING: Do not change the order, as
-      // `DEFAULT_REMOTE_TYPE` is a prefix of
-      // `FISSION_WEB_REMOTE_TYPE`.
-      type = mozilla::ProcType::WebIsolated;
-    } else if (StringBeginsWith(remoteType, SERVICEWORKER_REMOTE_TYPE)) {
-      type = mozilla::ProcType::WebServiceWorker;
-    } else if (StringBeginsWith(remoteType,
-                                WITH_COOP_COEP_REMOTE_TYPE_PREFIX)) {
-      type = mozilla::ProcType::WebCOOPCOEP;
-    } else if (remoteType == FILE_REMOTE_TYPE) {
-      type = mozilla::ProcType::File;
-    } else if (remoteType == EXTENSION_REMOTE_TYPE) {
-      type = mozilla::ProcType::Extension;
-    } else if (remoteType == PRIVILEGEDABOUT_REMOTE_TYPE) {
-      type = mozilla::ProcType::PrivilegedAbout;
-    } else if (remoteType == PRIVILEGEDMOZILLA_REMOTE_TYPE) {
-      type = mozilla::ProcType::PrivilegedMozilla;
-    } else if (remoteType == PREALLOC_REMOTE_TYPE) {
-      type = mozilla::ProcType::Preallocated;
-    } else if (remoteType == INFERENCE_REMOTE_TYPE) {
-      type = mozilla::ProcType::Inference;
-    } else if (StringBeginsWith(remoteType, DEFAULT_REMOTE_TYPE)) {
-      type = mozilla::ProcType::Web;
-    } else {
-      MOZ_CRASH_UNSAFE_PRINTF("Unknown remoteType '%s'", remoteType.get());
+    const RemoteType& remoteType = contentParent->GetRemoteType();
+    switch (remoteType.GetKind()) {
+      case RemoteType::Kind::WebContent:
+        type = remoteType.HasOrigin() ? mozilla::ProcType::WebIsolated
+                                      : mozilla::ProcType::Web;
+        break;
+      case RemoteType::Kind::WebServiceWorker:
+        type = mozilla::ProcType::WebServiceWorker;
+        break;
+      case RemoteType::Kind::WebCoopCoep:
+        type = mozilla::ProcType::WebCOOPCOEP;
+        break;
+      case RemoteType::Kind::File:
+        type = mozilla::ProcType::File;
+        break;
+      case RemoteType::Kind::Extension:
+        type = mozilla::ProcType::Extension;
+        break;
+      case RemoteType::Kind::PrivilegedAbout:
+        type = mozilla::ProcType::PrivilegedAbout;
+        break;
+      case RemoteType::Kind::PrivilegedMozilla:
+        type = mozilla::ProcType::PrivilegedMozilla;
+        break;
+      case RemoteType::Kind::Prealloc:
+        type = mozilla::ProcType::Preallocated;
+        break;
+      case RemoteType::Kind::Inference:
+        type = mozilla::ProcType::Inference;
+        break;
+      default: {
+        MOZ_CRASH_UNSAFE_PRINTF("Unknown remoteType '%s'",
+                                remoteType.StringifyKind().get());
+      }
     }
 
-    // By convention, everything after '=' is the origin.
-    nsAutoCString origin;
-    nsACString::const_iterator cursor;
-    nsACString::const_iterator end;
-    remoteType.BeginReading(cursor);
-    remoteType.EndReading(end);
-    if (FindCharInReadable('=', cursor, end)) {
-      origin = Substring(++cursor, end);
-    }
+    // FIXME: We should pass out a parsed remote type to the caller
+    nsAutoCString origin = remoteType.StringifyMeta();
 
     // Attach DOM window information to the process.
     nsTArray<WindowInfo> windows;
@@ -2608,7 +2608,13 @@ already_AddRefed<Promise> ChromeUtils::EnsureHeadlessContentProcess(
     return nullptr;
   }
 
-  ContentParent::GetNewOrUsedBrowserProcessAsync(aRemoteType)
+  RemoteType parsedRemoteType = RemoteType::Parse(aRemoteType);
+  if (!parsedRemoteType) {
+    promise->MaybeReject(NS_ERROR_INVALID_ARG);
+    return promise.forget();
+  }
+
+  ContentParent::GetNewOrUsedBrowserProcessAsync(parsedRemoteType)
       ->Then(
           GetCurrentSerialEventTarget(), __func__,
           [promise](UniqueContentParentKeepAlive&& aKeepAlive) {
@@ -3012,8 +3018,8 @@ void ChromeUtils::PredictRemoteTypeForURI(
     GlobalObject& aGlobal, nsIURI* aURI,
     const PredictRemoteTypeOptions& aOptions, nsACString& aRemoteType,
     ErrorResult& aRv) {
-  // If 'useRemoteTabs' is disabled, immediately return with NOT_REMOTE_TYPE,
-  // as we won't perform any process isolation.
+  // If 'useRemoteTabs' is disabled, immediately return with NotRemote as we
+  // won't perform any process isolation.
   bool useRemoteTabs = true;
   if (aOptions.mUseRemoteTabs.WasPassed()) {
     useRemoteTabs = aOptions.mUseRemoteTabs.Value();
@@ -3021,7 +3027,7 @@ void ChromeUtils::PredictRemoteTypeForURI(
     useRemoteTabs = aOptions.mWindow->GetBrowsingContext()->UseRemoteTabs();
   }
   if (!useRemoteTabs) {
-    aRemoteType = NOT_REMOTE_TYPE;
+    aRemoteType = RemoteType::NotRemote().Stringify();
     return;
   }
 
@@ -3042,14 +3048,22 @@ void ChromeUtils::PredictRemoteTypeForURI(
     attrs.mPrivateBrowsingId = aOptions.mWindow->IsPrivateBrowsing() ? 1 : 0;
   }
 
-  nsCString preferredRemoteType = aOptions.mPreferredRemoteType.WasPassed()
-                                      ? aOptions.mPreferredRemoteType.Value()
-                                      : SharedWebRemoteType(attrs);
+  RemoteType preferredRemoteType;
+  if (aOptions.mPreferredRemoteType.WasPassed()) {
+    preferredRemoteType =
+        RemoteType::Parse(aOptions.mPreferredRemoteType.Value());
+    if (!preferredRemoteType) {
+      aRv.ThrowTypeError("Invalid preferredRemoteType value");
+      return;
+    }
+  } else {
+    preferredRemoteType = RemoteType::SharedWeb(attrs);
+  }
 
   // If we got nullptr as our argument URI argument, treat it like an
   // about:blank document, and load it into our preferred remote type.
   if (!aURI) {
-    aRemoteType = preferredRemoteType;
+    aRemoteType = preferredRemoteType.Stringify();
     return;
   }
 
@@ -3060,7 +3074,7 @@ void ChromeUtils::PredictRemoteTypeForURI(
     return;
   }
 
-  aRemoteType = result.unwrap();
+  aRemoteType = result.unwrap().Stringify();
 }
 
 void ChromeUtils::PredictRemoteTypeForURI(
diff --git a/dom/base/nsFrameLoader.cpp b/dom/base/nsFrameLoader.cpp
index d956fdc0cb08..cbe296f25108 100644
--- a/dom/base/nsFrameLoader.cpp
+++ b/dom/base/nsFrameLoader.cpp
@@ -168,7 +168,7 @@ nsFrameLoader::nsFrameLoader(Element* aOwner, BrowsingContext* aBrowsingContext,
       mOwnerContent(aOwner),
       mPendingSwitchID(0),
       mChildID(0),
-      mRemoteType(NOT_REMOTE_TYPE),
+      mRemoteType(RemoteType::NotRemote()),
       mInitialized(false),
       mDepthTooGreat(false),
       mIsTopLevelContent(false),
@@ -418,24 +418,30 @@ already_AddRefed<nsFrameLoader> nsFrameLoader::Create(
   }
 
   bool isRemoteFrame = InitialLoadIsRemote(aOwner);
-  RefPtr<nsFrameLoader> fl =
-      new nsFrameLoader(aOwner, context, isRemoteFrame, aNetworkCreated);
-  fl->mOpenWindowInfo = aOpenWindowInfo;
 
   // If this is a toplevel initial remote frame, we're looking at a browser
   // loaded in the parent process. Pull the remote type attribute off of the
   // <browser> element to determine which remote type it should be loaded in, or
   // use a shared web remote type if we can't tell.
+  RemoteType remoteType;
   if (isRemoteFrame) {
     MOZ_ASSERT(XRE_IsParentProcess());
-    nsAutoString remoteType;
-    if (aOwner->GetAttr(nsGkAtoms::RemoteType, remoteType) &&
-        !remoteType.IsEmpty()) {
-      CopyUTF16toUTF8(remoteType, fl->mRemoteType);
+    nsAutoString remoteTypeAttr;
+    if (aOwner->GetAttr(nsGkAtoms::RemoteType, remoteTypeAttr) &&
+        !remoteTypeAttr.IsEmpty()) {
+      remoteType = RemoteType::Parse(NS_ConvertUTF16toUTF8(remoteTypeAttr));
+      NS_ENSURE_TRUE(remoteType, nullptr);
     } else {
-      fl->mRemoteType = SharedWebRemoteType(context->OriginAttributesRef());
+      remoteType = RemoteType::SharedWeb(context->OriginAttributesRef());
     }
+  } else {
+    remoteType = RemoteType::NotRemote();
   }
+
+  RefPtr<nsFrameLoader> fl =
+      new nsFrameLoader(aOwner, context, isRemoteFrame, aNetworkCreated);
+  fl->mOpenWindowInfo = aOpenWindowInfo;
+  fl->mRemoteType = remoteType;
   return fl.forget();
 }
 
@@ -541,7 +547,7 @@ void nsFrameLoader::LoadFrame(bool aOriginalSrc,
   }
 }
 
-void nsFrameLoader::ConfigRemoteProcess(const nsACString& aRemoteType,
+void nsFrameLoader::ConfigRemoteProcess(const RemoteType& aRemoteType,
                                         ContentParent* aContentParent) {
   MOZ_DIAGNOSTIC_ASSERT(IsRemoteFrame(), "Must be a remote frame");
   MOZ_DIAGNOSTIC_ASSERT(!mRemoteBrowser, "Must not have a browser yet");
diff --git a/dom/base/nsFrameLoader.h b/dom/base/nsFrameLoader.h
index 2db22ec9631e..7a6b7da2b866 100644
--- a/dom/base/nsFrameLoader.h
+++ b/dom/base/nsFrameLoader.h
@@ -25,6 +25,7 @@
 #include "mozilla/dom/Nullable.h"
 #include "mozilla/dom/Promise.h"
 #include "mozilla/dom/ReferrerPolicyBinding.h"
+#include "mozilla/dom/RemoteType.h"
 #include "mozilla/dom/WindowProxyHolder.h"
 #include "mozilla/dom/ipc/IdType.h"
 #include "mozilla/layers/LayersTypes.h"
@@ -406,7 +407,7 @@ class nsFrameLoader final : public nsStubMutationObserver,
   // `TryRemoteBrowser`, and a script blocker must be on the stack.
   //
   // |aContentParent|, if set, must have the remote type |aRemoteType|.
-  void ConfigRemoteProcess(const nsACString& aRemoteType,
+  void ConfigRemoteProcess(const mozilla::dom::RemoteType& aRemoteType,
                            mozilla::dom::ContentParent* aContentParent);
 
   // TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230)
@@ -526,7 +527,7 @@ class nsFrameLoader final : public nsStubMutationObserver,
   // refcounted cycles early.
   RefPtr<mozilla::dom::SessionStoreChild> mSessionStoreChild;
 
-  nsCString mRemoteType;
+  mozilla::dom::RemoteType mRemoteType;
 
   bool mInitialized : 1;
   bool mDepthTooGreat : 1;
diff --git a/dom/base/nsFrameLoaderOwner.cpp b/dom/base/nsFrameLoaderOwner.cpp
index a9653876477a..8708f93a5057 100644
--- a/dom/base/nsFrameLoaderOwner.cpp
+++ b/dom/base/nsFrameLoaderOwner.cpp
@@ -250,14 +250,18 @@ void nsFrameLoaderOwner::UpdateFocusAndMouseEnterStateAfterFrameLoaderChange(
 
 void nsFrameLoaderOwner::ChangeRemoteness(
     const mozilla::dom::RemotenessOptions& aOptions, mozilla::ErrorResult& rv) {
-  bool isRemote = !aOptions.mRemoteType.IsEmpty();
+  RemoteType remoteType = RemoteType::Parse(aOptions.mRemoteType);
+  if (!remoteType) {
+    rv.ThrowTypeError("Invalid RemoteType");
+    return;
+  }
 
   MOZ_RELEASE_ASSERT(mFrameLoader, "Expecting to have mFrameLoader here.");
   std::function<void()> frameLoaderInit = [&] {
     MOZ_RELEASE_ASSERT(mFrameLoader,
                        "Expecting still to have mFrameLoader here.");
-    if (isRemote) {
-      mFrameLoader->ConfigRemoteProcess(aOptions.mRemoteType, nullptr);
+    if (!remoteType.IsNotRemote()) {
+      mFrameLoader->ConfigRemoteProcess(remoteType, nullptr);
     }
 
     if (aOptions.mPendingSwitchID.WasPassed()) {
@@ -269,10 +273,11 @@ void nsFrameLoaderOwner::ChangeRemoteness(
   };
 
   auto shouldPreserve = ShouldPreserveBrowsingContext(
-      isRemote, /* replaceBrowsingContext */ false);
+      !remoteType.IsNotRemote(), /* replaceBrowsingContext */ false);
   NavigationIsolationOptions options;
   ChangeRemotenessCommon(shouldPreserve, options,
-                         aOptions.mSwitchingInProgressLoad, isRemote,
+                         aOptions.mSwitchingInProgressLoad,
+                         !remoteType.IsNotRemote(),
                          /* group */ nullptr, frameLoaderInit, rv);
 }
 
diff --git a/dom/clients/manager/ClientOpenWindowUtils.cpp b/dom/clients/manager/ClientOpenWindowUtils.cpp
index 0645a413447b..4f52b8b10644 100644
--- a/dom/clients/manager/ClientOpenWindowUtils.cpp
+++ b/dom/clients/manager/ClientOpenWindowUtils.cpp
@@ -366,7 +366,7 @@ void WaitForLoad(const ClientOpenWindowArgsParsed& aArgsValidated,
     loadState->SetTriggeringRemoteType(
         aArgsValidated.originContent
             ? aArgsValidated.originContent->GetRemoteType()
-            : NOT_REMOTE_TYPE);
+            : RemoteType::NotRemote());
 
     rv = aBrowsingContext->LoadURI(loadState, true);
     if (NS_FAILED(rv)) {
diff --git a/dom/clients/manager/ClientValidation.cpp b/dom/clients/manager/ClientValidation.cpp
index b8cd7167c07f..2e8fd8006a13 100644
--- a/dom/clients/manager/ClientValidation.cpp
+++ b/dom/clients/manager/ClientValidation.cpp
@@ -8,6 +8,7 @@
 #include "mozilla/dom/ClientIPCTypes.h"
 #include "mozilla/dom/LoadedOriginSet.h"
 #include "mozilla/dom/ProcessIsolation.h"
+#include "mozilla/dom/RemoteType.h"
 #include "mozilla/ipc/PBackgroundSharedTypes.h"
 #include "mozilla/net/MozURL.h"
 
diff --git a/dom/fetch/FetchParent.cpp b/dom/fetch/FetchParent.cpp
index e720acc51f1a..a36b784e2780 100644
--- a/dom/fetch/FetchParent.cpp
+++ b/dom/fetch/FetchParent.cpp
@@ -114,7 +114,7 @@ IPCResult FetchParent::RecvFetchOp(FetchOpArgs&& aArgs) {
     // The inference process uses ChromeWorkers which have a system principal,
     // so system principals must be allowed there.
     EnumSet<ValidatePrincipalOptions> options;
-    if (contentHandle->GetRemoteType() == INFERENCE_REMOTE_TYPE) {
+    if (contentHandle->GetRemoteType().IsInference()) {
       options += ValidatePrincipalOptions::AllowSystemIfLoaded;
     }
     if (!contentHandle->ValidatePrincipal(principal, options)) {
diff --git a/dom/fs/child/FileSystemBackgroundRequestHandler.cpp b/dom/fs/child/FileSystemBackgroundRequestHandler.cpp
index 2104859172fb..55bfba000a20 100644
--- a/dom/fs/child/FileSystemBackgroundRequestHandler.cpp
+++ b/dom/fs/child/FileSystemBackgroundRequestHandler.cpp
@@ -79,7 +79,7 @@ FileSystemBackgroundRequestHandler::CreateFileSystemManagerChild(
 
   // Throw if this process wouldn't be allowed to access storage.
   EnumSet<ValidatePrincipalOptions> options;
-  if (CurrentRemoteType() == INFERENCE_REMOTE_TYPE) {
+  if (CurrentRemoteType().IsInference()) {
     options += ValidatePrincipalOptions::AllowSystemIfLoaded;
   }
   if (!BackgroundChild::ValidatePrincipalInfo(aPrincipalInfo, options)) {
diff --git a/dom/ipc/BrowserChild.cpp b/dom/ipc/BrowserChild.cpp
index 36ec79dc9e3f..22df402700c5 100644
--- a/dom/ipc/BrowserChild.cpp
+++ b/dom/ipc/BrowserChild.cpp
@@ -2212,7 +2212,7 @@ already_AddRefed<DataTransfer> BrowserChild::ConvertToDataTransfer(
   // the principal permits it (and dom.events.datatransfer.protected.enabled is
   // false).  Otherwise, protected DataTransfer access should only be given to
   // the system.
-  if (!aPrincipal || Manager()->GetRemoteType() != EXTENSION_REMOTE_TYPE) {
+  if (!aPrincipal || !Manager()->GetRemoteType().IsExtension()) {
     aPrincipal = nsContentUtils::GetSystemPrincipal();
   }
 
diff --git a/dom/ipc/ContentChild.cpp b/dom/ipc/ContentChild.cpp
index bcda6d006242..8f1559c0a45a 100644
--- a/dom/ipc/ContentChild.cpp
+++ b/dom/ipc/ContentChild.cpp
@@ -646,7 +646,8 @@ ContentChild::ContentChild()
   {
     StaticMutexAutoLock lock(sLoadedOriginsMutex);
     MOZ_ASSERT(!sLoadedOrigins);
-    sLoadedOrigins = MakeRefPtr<LoadedOriginSet>(PREALLOC_REMOTE_TYPE);
+    sLoadedOrigins =
+        MakeRefPtr<LoadedOriginSet>(RemoteType(RemoteType::Kind::Prealloc));
     RunOnShutdown([] {
       StaticMutexAutoLock lock(sLoadedOriginsMutex);
       sLoadedOrigins = nullptr;
@@ -822,12 +823,8 @@ void ContentChild::Init(mozilla::ipc::UntypedEndpoint&& aEndpoint,
 }
 
 void ContentChild::AddProfileToProcessName(const nsACString& aProfile) {
-  nsCOMPtr<nsIPrincipal> isolationPrincipal =
-      ContentParent::CreateRemoteTypeIsolationPrincipal(mRemoteType);
-  if (isolationPrincipal) {
-    if (isolationPrincipal->OriginAttributesRef().IsPrivateBrowsing()) {
-      return;
-    }
+  if (mRemoteType.IsPrivateBrowsing()) {
+    return;
   }
 
   mProcessName = aProfile + ":"_ns + mProcessName;  //<profile_name>:example.com
@@ -861,35 +858,26 @@ void ContentChild::SetProcessName(const nsACString& aName,
 
   // Requires pref flip
   if (aSite && StaticPrefs::fission_processSiteNames()) {
-    nsCOMPtr<nsIPrincipal> isolationPrincipal =
-        ContentParent::CreateRemoteTypeIsolationPrincipal(mRemoteType);
-    if (isolationPrincipal) {
-      // DEFAULT_PRIVATE_BROWSING_ID is the value when it's not private
-      MOZ_LOG(ContentParent::GetLog(), LogLevel::Debug,
-              ("private = %d, pref = %d",
-               isolationPrincipal->OriginAttributesRef().IsPrivateBrowsing(),
-               StaticPrefs::fission_processPrivateWindowSiteNames()));
-      if (!isolationPrincipal->OriginAttributesRef().IsPrivateBrowsing()
+    // DEFAULT_PRIVATE_BROWSING_ID is the value when it's not private
+    MOZ_LOG(ContentParent::GetLog(), LogLevel::Debug,
+            ("private = %d, pref = %d", mRemoteType.IsPrivateBrowsing(),
+             StaticPrefs::fission_processPrivateWindowSiteNames()));
+    if (!mRemoteType.IsPrivateBrowsing()
 #ifdef NIGHTLY_BUILD
-          // Nightly can show site names for private windows, with a second pref
-          || StaticPrefs::fission_processPrivateWindowSiteNames()
+        // Nightly can show site names for private windows, with a second pref
+        || StaticPrefs::fission_processPrivateWindowSiteNames()
 #endif
-      ) {
+    ) {
 #if !defined(XP_MACOSX)
-        // Mac doesn't have the 15-character limit Linux does
-        // Sets profiler process name
-        if (isolationPrincipal->SchemeIs("https")) {
-          nsAutoCString schemeless;
-          isolationPrincipal->GetHostPort(schemeless);
-          nsAutoCString originSuffix;
-          isolationPrincipal->GetOriginSuffix(originSuffix);
-          schemeless.Append(originSuffix);
-          mProcessName = std::move(schemeless);
-        } else
+      // Mac doesn't have the 15-character limit Linux does
+      // Sets profiler process name
+      constexpr nsLiteralCString prefix = "https://"_ns;
+      if (StringBeginsWith(*aSite, prefix)) {
+        mProcessName = Substring(*aSite, prefix.Length());
+      } else
 #endif
-        {
-          mProcessName = *aSite;
-        }
+      {
+        mProcessName = *aSite;
       }
     }
   }
@@ -1288,11 +1276,11 @@ void ContentChild::MaybeBecomeUntrusted() {
   }
 
   ContentChild* cc = ContentChild::GetSingleton();
-  MOZ_DIAGNOSTIC_ASSERT(cc->GetRemoteType() != PREALLOC_REMOTE_TYPE,
+  MOZ_DIAGNOSTIC_ASSERT(!cc->GetRemoteType().IsPrealloc(),
                         "Prealloc process cannot become untrusted");
 
   // Never mark the privilegedabout process as untrusted.
-  if (cc->GetRemoteType() == PRIVILEGEDABOUT_REMOTE_TYPE) {
+  if (cc->GetRemoteType().IsPrivilegedAbout()) {
     return;
   }
 
@@ -1358,7 +1346,7 @@ void ContentChild::InitXPCOM(
 
   ClientManager::Startup();
 
-  // RemoteWorkerService will be initialized in RecvRemoteType, to avoid to
+  // RemoteWorkerService will be initialized in RecvSetRemoteType, to avoid to
   // register it to the RemoteWorkerManager while it is still a prealloc
   // remoteType and defer it to the point the child process is assigned a.
   // actual remoteType.
@@ -1454,10 +1442,10 @@ mozilla::ipc::IPCResult ContentChild::RecvRequestMemoryReport(
     const Maybe<mozilla::ipc::FileDescriptor>& aDMDFile,
     const RequestMemoryReportResolver& aResolver) {
   nsCString process;
-  if (aAnonymize || mRemoteType.IsEmpty()) {
+  if (aAnonymize || !mRemoteType.IsKnown()) {
     GetProcessName(process);
   } else {
-    process = mRemoteType;
+    process = mRemoteType.Stringify();
   }
   AppendProcessId(process);
   MOZ_ASSERT(!process.IsEmpty());
@@ -2705,15 +2693,15 @@ mozilla::ipc::IPCResult ContentChild::RecvAppInfo(
   return IPC_OK();
 }
 
-nsCString CurrentRemoteType() {
+RemoteType CurrentRemoteType() {
   if (XRE_IsContentProcess()) {
     if (RefPtr<LoadedOriginSet> loadedOrigins = CurrentLoadedOriginSet()) {
       return loadedOrigins->GetRemoteType();
     }
-    return PREALLOC_REMOTE_TYPE;
+    return RemoteType(RemoteType::Kind::Prealloc);
   }
 
-  return NOT_REMOTE_TYPE;
+  return RemoteType::NotRemote();
 }
 
 already_AddRefed<LoadedOriginSet> CurrentLoadedOriginSet() {
@@ -2721,40 +2709,37 @@ already_AddRefed<LoadedOriginSet> CurrentLoadedOriginSet() {
   return do_AddRef(sLoadedOrigins);
 }
 
-mozilla::ipc::IPCResult ContentChild::RecvRemoteType(
-    const nsCString& aRemoteType, const nsCString& aProfile) {
+mozilla::ipc::IPCResult ContentChild::RecvSetRemoteType(
+    const RemoteType& aRemoteType, const nsCString& aProfile) {
   if (aRemoteType == mRemoteType) {
     // Allocation of preallocated processes that are still launching can
     // cause this
     return IPC_OK();
   }
 
-  if (!mRemoteType.IsVoid()) {
-    // Preallocated processes are type PREALLOC_REMOTE_TYPE; they may not
-    // become a File: process, or Privileged About Content Process
+  if (mRemoteType.IsKnown()) {
     MOZ_LOG(ContentParent::GetLog(), LogLevel::Debug,
             ("Changing remoteType of process %d from %s to %s", getpid(),
-             mRemoteType.get(), aRemoteType.get()));
-    // prealloc->anything (but file) or web->web allowed, and no-change
-    MOZ_RELEASE_ASSERT(mRemoteType == PREALLOC_REMOTE_TYPE &&
-                       aRemoteType != FILE_REMOTE_TYPE &&
-                       aRemoteType != PRIVILEGEDABOUT_REMOTE_TYPE);
+             mRemoteType.Stringify().get(), aRemoteType.Stringify().get()));
+    MOZ_RELEASE_ASSERT(
+        mRemoteType.IsPrealloc(),
+        "Cannot change remote type unless we're a prealloc process");
+    MOZ_RELEASE_ASSERT(aRemoteType.SupportsPrealloc(),
+                       "Cannot use prealloc process for this remote type");
   } else {
     // Initial setting of remote type.  Either to 'prealloc' or the actual
     // final type (if we didn't use a preallocated process)
     MOZ_LOG(ContentParent::GetLog(), LogLevel::Debug,
             ("Setting remoteType of process %d to %s", getpid(),
-             aRemoteType.get()));
+             aRemoteType.Stringify().get()));
 
-    if (aRemoteType == PREALLOC_REMOTE_TYPE) {
+    if (aRemoteType.IsPrealloc()) {
       PreallocInit();
     }
   }
 
-  auto remoteTypePrefix = RemoteTypePrefix(aRemoteType);
-
   // Must do before SetProcessName
-  mRemoteType.Assign(aRemoteType);
+  mRemoteType = aRemoteType;
 
   RefPtr<LoadedOriginSet> loadedOrigins = CurrentLoadedOriginSet();
   if (!loadedOrigins) {
@@ -2763,36 +2748,32 @@ mozilla::ipc::IPCResult ContentChild::RecvRemoteType(
   loadedOrigins->SetRemoteType(mRemoteType);
 
   // Update the process name so about:memory's process names are more obvious.
-  if (aRemoteType == FILE_REMOTE_TYPE) {
+  if (aRemoteType.IsFile()) {
     SetProcessName("file:// Content"_ns, nullptr, &aProfile);
-  } else if (aRemoteType == EXTENSION_REMOTE_TYPE) {
+  } else if (aRemoteType.IsExtension()) {
     SetProcessName("WebExtensions"_ns, nullptr, &aProfile);
-  } else if (aRemoteType == PRIVILEGEDABOUT_REMOTE_TYPE) {
+  } else if (aRemoteType.IsPrivilegedAbout()) {
     SetProcessName("Privileged Content"_ns, nullptr, &aProfile);
-  } else if (aRemoteType == PRIVILEGEDMOZILLA_REMOTE_TYPE) {
+  } else if (aRemoteType.IsPrivilegedMozilla()) {
     SetProcessName("Privileged Mozilla"_ns, nullptr, &aProfile);
-  } else if (aRemoteType == INFERENCE_REMOTE_TYPE) {
+  } else if (aRemoteType.IsInference()) {
     SetProcessName("Inference"_ns, nullptr, &aProfile);
-  } else if (remoteTypePrefix == WITH_COOP_COEP_REMOTE_TYPE) {
-    // The profiler can sanitize out the eTLD+1
-    nsDependentCSubstring etld =
-        Substring(aRemoteType, WITH_COOP_COEP_REMOTE_TYPE.Length() + 1);
+  } else if (aRemoteType.IsIsolatedWeb()) {
+    nsAutoCString site = mRemoteType.StringifyMeta();
+
+    if (aRemoteType.IsWebServiceWorker()) {
+      SetProcessName("Isolated Service Worker"_ns, &site, &aProfile);
+    }
 #ifdef NIGHTLY_BUILD
-    SetProcessName("WebCOOP+COEP Content"_ns, &etld, &aProfile);
-#else
-    SetProcessName("Isolated Web Content"_ns, &etld,
-                   &aProfile);  // to avoid confusing people
+    else if (aRemoteType.IsWebCoopCoep()) {
+      // NOTE: We only distinguish between isolated web sub-types on Nightly
+      // builds to avoid confusing users.
+      SetProcessName("WebCOOP+COEP Content"_ns, &site, &aProfile);
+    }
 #endif
-  } else if (remoteTypePrefix == FISSION_WEB_REMOTE_TYPE) {
-    // The profiler can sanitize out the eTLD+1
-    nsDependentCSubstring etld =
-        Substring(aRemoteType, FISSION_WEB_REMOTE_TYPE.Length() + 1);
-    SetProcessName("Isolated Web Content"_ns, &etld, &aProfile);
-  } else if (remoteTypePrefix == SERVICEWORKER_REMOTE_TYPE) {
-    // The profiler can sanitize out the eTLD+1
-    nsDependentCSubstring etld =
-        Substring(aRemoteType, SERVICEWORKER_REMOTE_TYPE.Length() + 1);
-    SetProcessName("Isolated Service Worker"_ns, &etld, &aProfile);
+    else {
+      SetProcessName("Isolated Web Content"_ns, &site, &aProfile);
+    }
   } else {
     // else "prealloc" or "web" type -> "Web Content"
     SetProcessName("Web Content"_ns, nullptr, &aProfile);
@@ -2801,17 +2782,15 @@ mozilla::ipc::IPCResult ContentChild::RecvRemoteType(
   // Turn off Spectre mitigations in isolated web content processes.
   if (StaticPrefs::javascript_options_spectre_disable_for_isolated_content() &&
       StaticPrefs::browser_opaqueResponseBlocking() &&
-      (remoteTypePrefix == FISSION_WEB_REMOTE_TYPE ||
-       remoteTypePrefix == SERVICEWORKER_REMOTE_TYPE ||
-       remoteTypePrefix == WITH_COOP_COEP_REMOTE_TYPE ||
-       aRemoteType == PRIVILEGEDABOUT_REMOTE_TYPE ||
-       aRemoteType == PRIVILEGEDMOZILLA_REMOTE_TYPE)) {
+      (aRemoteType.IsIsolatedWeb() || aRemoteType.IsPrivilegedAbout() ||
+       aRemoteType.IsPrivilegedMozilla())) {
     JS::DisableSpectreMitigationsAfterInit();
   }
 
-  // Use the prefix to avoid URIs from Fission isolated processes.
+  // Only include the kind, as we don't want to include URIs from
+  // Fission-isolated processes.
   CrashReporter::RecordAnnotationNSCString(
-      CrashReporter::Annotation::RemoteType, remoteTypePrefix);
+      CrashReporter::Annotation::RemoteType, mRemoteType.StringifyKind());
 
   return IPC_OK();
 }
@@ -2845,9 +2824,9 @@ void ContentChild::PreallocInit() {
   nsHttpHandler::PresetAcceptLanguages();
 }
 
-// Call RemoteTypePrefix() on the result to remove URIs if you want to use this
+// Call .StringifyKind() on the result to remove URIs if you want to use this
 // for telemetry.
-const nsACString& ContentChild::GetRemoteType() const { return mRemoteType; }
+const RemoteType& ContentChild::GetRemoteType() const { return mRemoteType; }
 
 mozilla::ipc::IPCResult ContentChild::RecvInitRemoteWorkerService(
     Endpoint<PRemoteWorkerServiceChild>&& aEndpoint,
@@ -3541,7 +3520,7 @@ mozilla::ipc::IPCResult ContentChild::RecvCrossProcessRedirect(
 
   nsCOMPtr<nsILoadInfo> loadInfo;
   nsresult rv = mozilla::ipc::LoadInfoArgsToLoadInfo(
-      aArgs.loadInfo(), NOT_REMOTE_TYPE, getter_AddRefs(loadInfo));
+      aArgs.loadInfo(), RemoteType::NotRemote(), getter_AddRefs(loadInfo));
   if (NS_FAILED(rv)) {
     MOZ_DIAGNOSTIC_CRASH("LoadInfoArgsToLoadInfo failed");
     return IPC_OK();
@@ -4350,7 +4329,7 @@ mozilla::ipc::IPCResult ContentChild::RecvReportFrameTimingData(
 
   nsCOMPtr<nsILoadInfo> loadInfo;
   nsresult rv = mozilla::ipc::LoadInfoArgsToLoadInfo(
-      loadInfoArgs, NOT_REMOTE_TYPE, getter_AddRefs(loadInfo));
+      loadInfoArgs, RemoteType::NotRemote(), getter_AddRefs(loadInfo));
   if (NS_FAILED(rv)) {
     MOZ_DIAGNOSTIC_CRASH("LoadInfoArgsToLoadInfo failed");
     return IPC_OK();
diff --git a/dom/ipc/ContentChild.h b/dom/ipc/ContentChild.h
index f458695782e1..0b347d487450 100644
--- a/dom/ipc/ContentChild.h
+++ b/dom/ipc/ContentChild.h
@@ -69,6 +69,7 @@ class SharedMap;
 
 class ConsoleListener;
 class BrowserChild;
+class IPCTabContext;
 class TabContext;
 enum class CallerType : uint32_t;
 
@@ -393,14 +394,12 @@ class ContentChild final : public PContentChild,
       const nsCString& UAName, const nsCString& ID, const nsCString& vendor,
       const nsCString& sourceURL, const nsCString& updateURL);
 
-  mozilla::ipc::IPCResult RecvRemoteType(const nsCString& aRemoteType,
-                                         const nsCString& aProfile);
+  mozilla::ipc::IPCResult RecvSetRemoteType(const RemoteType& aRemoteType,
+                                            const nsCString& aProfile);
 
   void PreallocInit();
 
-  // Call RemoteTypePrefix() on the result to remove URIs if you want to use
-  // this for telemetry.
-  const nsACString& GetRemoteType() const override;
+  const RemoteType& GetRemoteType() const override;
 
   mozilla::ipc::IPCResult RecvAddLoadedOrigin(nsIPrincipal* aPrincipal);
 
@@ -906,7 +905,7 @@ class ContentChild final : public PContentChild,
   AppInfo mAppInfo;
 
   bool mIsForBrowser;
-  nsCString mRemoteType = NOT_REMOTE_TYPE;
+  RemoteType mRemoteType;
   bool mIsAlive;
   nsCString mProcessName;
 
@@ -960,7 +959,7 @@ inline nsISupports* ToSupports(mozilla::dom::ContentChild* aContentChild) {
 }
 
 // Threadsafe getter for the current process's RemoteType.
-nsCString CurrentRemoteType();
+RemoteType CurrentRemoteType();
 
 // Threadsafe getter for the current process's loaded origins.
 already_AddRefed<LoadedOriginSet> CurrentLoadedOriginSet();
diff --git a/dom/ipc/ContentParent.cpp b/dom/ipc/ContentParent.cpp
index 9fa589c251da..54567ebeff9f 100644
--- a/dom/ipc/ContentParent.cpp
+++ b/dom/ipc/ContentParent.cpp
@@ -580,18 +580,17 @@ ContentParentsMemoryReporter::CollectReports(
 // processes that are in the Preallocator cache (which would be type
 // 'prealloc'), and recycled processes ('web' and in the future
 // eTLD+1-locked) processes).
-nsClassHashtable<nsCStringHashKey, nsTArray<ContentParent*>>*
+nsClassHashtable<nsGenericHashKey<RemoteType>, nsTArray<ContentParent*>>*
     ContentParent::sBrowserContentParents;
 
 namespace {
 
-ProcessID GetTelemetryProcessID(const nsACString& remoteType) {
+ProcessID GetTelemetryProcessID(const RemoteType& remoteType) {
   // OOP WebExtensions run in a content process.
   // For Telemetry though we want to break out collected data from the
   // WebExtensions process into a separate bucket, to make sure we can analyze
   // it separately and avoid skewing normal content process metrics.
-  return remoteType == EXTENSION_REMOTE_TYPE ? ProcessID::Extension
-                                             : ProcessID::Content;
+  return remoteType.IsExtension() ? ProcessID::Extension : ProcessID::Content;
 }
 
 }  // anonymous namespace
@@ -649,7 +648,8 @@ void ContentParent_NotifyUpdatedDictionaries() {
 // PreallocateProcess is called by the PreallocatedProcessManager.
 // ContentParent then takes this process back within GetNewOrUsedBrowserProcess.
 /*static*/ UniqueContentParentKeepAlive ContentParent::MakePreallocProcess() {
-  RefPtr<ContentParent> process = new ContentParent(PREALLOC_REMOTE_TYPE);
+  RefPtr<ContentParent> process =
+      new ContentParent(RemoteType(RemoteType::Kind::Prealloc));
   if (NS_WARN_IF(!process->BeginSubprocessLaunch(PROCESS_PRIORITY_PREALLOC))) {
     process->LaunchSubprocessReject();
     return nullptr;
@@ -704,7 +704,7 @@ void ContentParent::ShutDown() {
 }
 
 /*static*/
-uint32_t ContentParent::GetPoolSize(const nsACString& aContentProcessType) {
+uint32_t ContentParent::GetPoolSize(const RemoteType& aContentProcessType) {
   if (!sBrowserContentParents) {
     return 0;
   }
@@ -716,74 +716,20 @@ uint32_t ContentParent::GetPoolSize(const nsACString& aContentProcessType) {
 }
 
 /*static*/ nsTArray<ContentParent*>& ContentParent::GetOrCreatePool(
-    const nsACString& aContentProcessType) {
+    const RemoteType& aContentProcessType) {
   if (!sBrowserContentParents) {
-    sBrowserContentParents =
-        new nsClassHashtable<nsCStringHashKey, nsTArray<ContentParent*>>;
+    sBrowserContentParents = new nsClassHashtable<nsGenericHashKey<RemoteType>,
+                                                  nsTArray<ContentParent*>>;
   }
 
   return *sBrowserContentParents->GetOrInsertNew(aContentProcessType);
 }
 
-nsDependentCSubstring RemoteTypePrefix(const nsACString& aContentProcessType) {
-  // The suffix after a `=` in a remoteType is dynamic, and used to control the
-  // process pool to use.
-  int32_t equalIdx = aContentProcessType.FindChar(L'=');
-  if (equalIdx == kNotFound) {
-    equalIdx = aContentProcessType.Length();
-  }
-  return StringHead(aContentProcessType, equalIdx);
-}
-
-static bool IsRemoteTypeJitDisabled(const nsACString& aContentProcessType) {
-  if (!StringEndsWith(aContentProcessType, DISABLE_JIT_REMOTE_TYPE_SUFFIX)) {
-    return false;
-  }
-
-  auto remoteTypePrefix = RemoteTypePrefix(aContentProcessType);
-  if (remoteTypePrefix != FISSION_WEB_REMOTE_TYPE &&
-      remoteTypePrefix != SERVICEWORKER_REMOTE_TYPE &&
-      remoteTypePrefix != WITH_COOP_COEP_REMOTE_TYPE) {
-    return false;
-  }
-
-  auto suffixStart =
-      aContentProcessType.Length() - DISABLE_JIT_REMOTE_TYPE_SUFFIX.Length();
-  if (suffixStart > 0) {
-    char priorChar = aContentProcessType[suffixStart - 1];
-    if (priorChar != '&' && priorChar != '^') {
-      return false;
-    }
-  } else {
-    return false;
-  }
-
-  return true;
-}
-
-bool IsWebRemoteType(const nsACString& aContentProcessType) {
-  // Note: matches webIsolated, web, and webCOOP+COEP types.
-  return StringBeginsWith(aContentProcessType, DEFAULT_REMOTE_TYPE);
-}
-
-bool IsWebCoopCoepRemoteType(const nsACString& aContentProcessType) {
-  return StringBeginsWith(aContentProcessType,
-                          WITH_COOP_COEP_REMOTE_TYPE_PREFIX);
-}
-
-bool IsExtensionRemoteType(const nsACString& aContentProcessType) {
-  return aContentProcessType == EXTENSION_REMOTE_TYPE;
-}
-
 /*static*/
 uint32_t ContentParent::GetMaxProcessCount(
-    const nsACString& aContentProcessType) {
-  // Max process count is based only on the prefix.
-  const nsDependentCSubstring processTypePrefix =
-      RemoteTypePrefix(aContentProcessType);
-
-  // Check for the default remote type of "web", as it uses different prefs.
-  if (processTypePrefix == DEFAULT_REMOTE_TYPE) {
+    const RemoteType& aContentProcessType) {
+  // Check for the shared web remote type, as it uses different prefs.
+  if (aContentProcessType.IsSharedWeb()) {
     return GetMaxWebProcessCount();
   }
 
@@ -791,7 +737,7 @@ uint32_t ContentParent::GetMaxProcessCount(
   // used as a fallback, as it is intended to control the number of "web"
   // content processes, checked in `mozilla::GetMaxWebProcessCount()`.
   nsAutoCString processCountPref("dom.ipc.processCount.");
-  processCountPref.Append(processTypePrefix);
+  processCountPref.Append(aContentProcessType.StringifyKind());
 
   int32_t maxContentParents = Preferences::GetInt(processCountPref.get(), 1);
   if (maxContentParents < 1) {
@@ -803,7 +749,7 @@ uint32_t ContentParent::GetMaxProcessCount(
 
 /*static*/
 bool ContentParent::IsMaxProcessCountReached(
-    const nsACString& aContentProcessType) {
+    const RemoteType& aContentProcessType) {
   return GetPoolSize(aContentProcessType) >=
          GetMaxProcessCount(aContentProcessType);
 }
@@ -820,7 +766,7 @@ void ContentParent::ReleaseCachedProcesses() {
 #ifdef DEBUG
   for (const auto& cps : *sBrowserContentParents) {
     MOZ_LOG(ContentParent::GetLog(), LogLevel::Debug,
-            ("%s: %zu processes", PromiseFlatCString(cps.GetKey()).get(),
+            ("%s: %zu processes", cps.GetKey().Stringify().get(),
              cps.GetData()->Length()));
   }
 #endif
@@ -892,29 +838,9 @@ already_AddRefed<ContentParent> ContentParent::MinTabSelect(
   return candidate.forget();
 }
 
-/* static */
-already_AddRefed<nsIPrincipal>
-ContentParent::CreateRemoteTypeIsolationPrincipal(
-    const nsACString& aRemoteType) {
-  if ((RemoteTypePrefix(aRemoteType) != FISSION_WEB_REMOTE_TYPE) &&
-      !StringBeginsWith(aRemoteType, WITH_COOP_COEP_REMOTE_TYPE_PREFIX)) {
-    return nullptr;
-  }
-
-  int32_t offset = aRemoteType.FindChar('=') + 1;
-  MOZ_ASSERT(offset > 1, "can not extract origin from that remote type");
-  nsAutoCString origin(
-      Substring(aRemoteType, offset, aRemoteType.Length() - offset));
-
-  nsIScriptSecurityManager* ssm = nsContentUtils::GetSecurityManager();
-  nsCOMPtr<nsIPrincipal> principal;
-  ssm->CreateContentPrincipalFromOrigin(origin, getter_AddRefs(principal));
-  return principal.forget();
-}
-
 /*static*/
 UniqueContentParentKeepAlive ContentParent::GetUsedBrowserProcess(
-    const nsACString& aRemoteType, nsTArray<ContentParent*>& aContentParents,
+    const RemoteType& aRemoteType, nsTArray<ContentParent*>& aContentParents,
     uint32_t aMaxContentParents, bool aPreferUsed, ProcessPriority aPriority,
     uint64_t aBrowserId) {
 #ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
@@ -944,7 +870,7 @@ UniqueContentParentKeepAlive ContentParent::GetUsedBrowserProcess(
     MOZ_LOG(ContentParent::GetLog(), LogLevel::Debug,
             ("GetUsedProcess: Reused process id=%p childID=%" PRIu64 " for %s",
              selected.get(), (uint64_t)selected->ChildID(),
-             PromiseFlatCString(aRemoteType).get()));
+             aRemoteType.Stringify().get()));
     selected->AssertAlive();
     return selected->AddKeepAlive(aBrowserId);
   }
@@ -952,13 +878,9 @@ UniqueContentParentKeepAlive ContentParent::GetUsedBrowserProcess(
   // Try to take a preallocated process except for certain remote types.
   // Note: this process may not have finished launching yet
   UniqueContentParentKeepAlive preallocated;
-  if (aRemoteType != FILE_REMOTE_TYPE &&
-      aRemoteType != PRIVILEGEDABOUT_REMOTE_TYPE &&
-      aRemoteType != EXTENSION_REMOTE_TYPE &&  // Bug 1638119
-      !IsRemoteTypeJitDisabled(aRemoteType) &&
+  if (aRemoteType.SupportsPrealloc() &&
       (preallocated = PreallocatedProcessManager::Take(aRemoteType))) {
-    MOZ_DIAGNOSTIC_ASSERT(preallocated->GetRemoteType() ==
-                          PREALLOC_REMOTE_TYPE);
+    MOZ_DIAGNOSTIC_ASSERT(preallocated->GetRemoteType().IsPrealloc());
     preallocated->AssertAlive();
 
     if (profiler_thread_is_being_profiled_for_markers()) {
@@ -972,20 +894,18 @@ UniqueContentParentKeepAlive ContentParent::GetUsedBrowserProcess(
         ContentParent::GetLog(), LogLevel::Debug,
         ("Adopted preallocated process id=%p childID=%" PRIu64 " for type %s%s",
          preallocated.get(), (uint64_t)preallocated->ChildID(),
-         PromiseFlatCString(aRemoteType).get(),
+         aRemoteType.Stringify().get(),
          preallocated->IsLaunching() ? " (still launching)" : ""));
 
-    MOZ_LOG(mozilla::ipc::gChildProcessLifecycleLog, LogLevel::Info,
-            ("REMOTETYPE [childID = %" PRIi32 "] [remoteType = %s]",
-             preallocated->Process()->GetChildID(),
-             PromiseFlatCString(aRemoteType).get()));
+    MOZ_LOG(
+        mozilla::ipc::gChildProcessLifecycleLog, LogLevel::Info,
+        ("REMOTETYPE [childID = %" PRIi32 "] [remoteType = %s]",
+         preallocated->Process()->GetChildID(), aRemoteType.Stringify().get()));
 
     // This ensures that the preallocator won't shut down the process once
     // it finishes starting
-    preallocated->mRemoteType.Assign(aRemoteType);
+    preallocated->mRemoteType = aRemoteType;
     preallocated->LoadedOrigins()->SetRemoteType(preallocated->mRemoteType);
-    preallocated->mRemoteTypeIsolationPrincipal =
-        CreateRemoteTypeIsolationPrincipal(aRemoteType);
     preallocated->AddToPool(aContentParents);
 
     // rare, but will happen
@@ -993,8 +913,8 @@ UniqueContentParentKeepAlive ContentParent::GetUsedBrowserProcess(
       // Specialize this process for the appropriate remote type, and activate
       // it.
 
-      (void)preallocated->SendRemoteType(preallocated->mRemoteType,
-                                         preallocated->mProfile);
+      (void)preallocated->SendSetRemoteType(preallocated->mRemoteType,
+                                            preallocated->mProfile);
 
       preallocated->StartRemoteWorkerService();
 
@@ -1019,11 +939,10 @@ UniqueContentParentKeepAlive ContentParent::GetUsedBrowserProcess(
 
 /*static*/
 UniqueContentParentKeepAlive ContentParent::GetNewOrUsedLaunchingBrowserProcess(
-    const nsACString& aRemoteType, BrowsingContextGroup* aGroup,
+    const RemoteType& aRemoteType, BrowsingContextGroup* aGroup,
     ProcessPriority aPriority, bool aPreferUsed, uint64_t aBrowserId) {
   MOZ_LOG(ContentParent::GetLog(), LogLevel::Debug,
-          ("GetNewOrUsedProcess for type %s",
-           PromiseFlatCString(aRemoteType).get()));
+          ("GetNewOrUsedProcess for type %s", aRemoteType.Stringify().get()));
 
   if (AppShutdown::IsInOrBeyond(ShutdownPhase::AppShutdownConfirmed)) {
     return nullptr;
@@ -1063,7 +982,7 @@ UniqueContentParentKeepAlive ContentParent::GetNewOrUsedLaunchingBrowserProcess(
     // The life cycle will be set to `LifecycleState::LAUNCHING`.
     MOZ_LOG(ContentParent::GetLog(), LogLevel::Debug,
             ("Launching new process immediately for type %s",
-             PromiseFlatCString(aRemoteType).get()));
+             aRemoteType.Stringify().get()));
 
     RefPtr<ContentParent> newCp = new ContentParent(aRemoteType);
     if (NS_WARN_IF(!newCp->BeginSubprocessLaunch(aPriority))) {
@@ -1099,7 +1018,7 @@ UniqueContentParentKeepAlive ContentParent::GetNewOrUsedLaunchingBrowserProcess(
 
 /*static*/
 RefPtr<ContentParent::LaunchPromise>
-ContentParent::GetNewOrUsedBrowserProcessAsync(const nsACString& aRemoteType,
+ContentParent::GetNewOrUsedBrowserProcessAsync(const RemoteType& aRemoteType,
                                                BrowsingContextGroup* aGroup,
                                                ProcessPriority aPriority,
                                                bool aPreferUsed,
@@ -1118,7 +1037,7 @@ ContentParent::GetNewOrUsedBrowserProcessAsync(const nsACString& aRemoteType,
 
 /*static*/
 UniqueContentParentKeepAlive ContentParent::GetNewOrUsedBrowserProcess(
-    const nsACString& aRemoteType, BrowsingContextGroup* aGroup,
+    const RemoteType& aRemoteType, BrowsingContextGroup* aGroup,
     ProcessPriority aPriority, bool aPreferUsed, uint64_t aBrowserId) {
   UniqueContentParentKeepAlive contentParent =
       GetNewOrUsedLaunchingBrowserProcess(aRemoteType, aGroup, aPriority,
@@ -1372,7 +1291,7 @@ NS_IMETHODIMP ContentParent::ValidatePrincipalXPCOM(nsIPrincipal* aPrincipal,
 /*static*/
 already_AddRefed<RemoteBrowser> ContentParent::CreateBrowser(
     const TabContext& aContext, Element* aFrameElement,
-    const nsACString& aRemoteType, BrowsingContext* aBrowsingContext,
+    const RemoteType& aRemoteType, BrowsingContext* aBrowsingContext,
     ContentParent* aOpenerContentParent) {
   AUTO_PROFILER_LABEL("ContentParent::CreateBrowser", OTHER);
 
@@ -1389,9 +1308,9 @@ already_AddRefed<RemoteBrowser> ContentParent::CreateBrowser(
     return nullptr;
   }
 
-  nsAutoCString remoteType(aRemoteType);
-  if (remoteType.IsEmpty()) {
-    remoteType = SharedWebRemoteType(aBrowsingContext->OriginAttributesRef());
+  RemoteType remoteType(aRemoteType);
+  if (!remoteType.IsKnown() || remoteType.IsNotRemote()) {
+    remoteType = RemoteType::SharedWeb(aBrowsingContext->OriginAttributesRef());
   }
 
   TabId tabId(nsContentUtils::GenerateTabId());
@@ -1599,7 +1518,7 @@ void ContentParent::BroadcastMediaCodecsSupportedUpdate(
   }
 }
 
-const nsACString& ContentParent::GetRemoteType() const { return mRemoteType; }
+const RemoteType& ContentParent::GetRemoteType() const { return mRemoteType; }
 
 static StaticRefPtr<nsIAsyncShutdownClient> sXPCOMShutdownClient;
 static StaticRefPtr<nsIAsyncShutdownClient> sProfileBeforeChangeClient;
@@ -2182,7 +2101,7 @@ void ContentParent::MaybeBeginShutDown(bool aImmediate,
       aImmediate || IsDead() ||
       AppShutdown::IsInOrBeyond(ShutdownPhase::AppShutdownConfirmed) ||
       StaticPrefs::dom_ipc_processReuse_unusedGraceMs() == 0 ||
-      IsRemoteTypeJitDisabled(mRemoteType);
+      mRemoteType.IsJitDisabled();
 
   // Clean up any scheduled idle task unless we schedule a new one.
   auto cancelIdleTask = MakeScopeExit([&] {
@@ -2205,7 +2124,7 @@ void ContentParent::MaybeBeginShutDown(bool aImmediate,
     // processes alive for performance reasons (e.g. test runs and privileged
     // content process for some about: pages). We don't want to alter behavior
     // if the pref is not set, so default to 0.
-    if (!aIgnoreKeepAlivePref && mIsInPool && !mRemoteType.Contains('=') &&
+    if (!aIgnoreKeepAlivePref && mIsInPool && !mRemoteType.HasMeta() &&
         !AppShutdown::IsInOrBeyond(ShutdownPhase::AppShutdownConfirmed)) {
       auto* contentParents = sBrowserContentParents->Get(mRemoteType);
       MOZ_RELEASE_ASSERT(
@@ -2213,7 +2132,7 @@ void ContentParent::MaybeBeginShutDown(bool aImmediate,
           "mIsInPool, yet no entry for mRemoteType in sBrowserContentParents?");
 
       nsAutoCString keepAlivePref("dom.ipc.keepProcessesAlive.");
-      keepAlivePref.Append(mRemoteType);
+      keepAlivePref.Append(mRemoteType.StringifyKind());
 
       int32_t processesToKeepAlive = 0;
       if (NS_SUCCEEDED(Preferences::GetInt(keepAlivePref.get(),
@@ -2335,7 +2254,7 @@ already_AddRefed<TestShellParent> ContentParent::GetTestShellSingleton() {
 void ContentParent::AppendDynamicSandboxParams(
     std::vector<std::string>& aArgs) {
   // For file content processes
-  if (GetRemoteType() == FILE_REMOTE_TYPE) {
+  if (GetRemoteType().IsFile()) {
     MacSandboxInfo::AppendFileAccessParam(aArgs, true);
   }
 }
@@ -2499,7 +2418,7 @@ bool ContentParent::BeginSubprocessLaunch(ProcessPriority aPriority) {
   Preferences::AddStrongObserver(this, "");
 
   geckoargs::sSafeMode.Put(gSafeMode, extraArgs);
-  geckoargs::sDisableJit.Put(IsRemoteTypeJitDisabled(mRemoteType), extraArgs);
+  geckoargs::sDisableJit.Put(mRemoteType.IsJitDisabled(), extraArgs);
 
 #if defined(XP_MACOSX) && defined(MOZ_SANDBOX)
   if (IsContentSandboxEnabled()) {
@@ -2520,7 +2439,7 @@ bool ContentParent::BeginSubprocessLaunch(ProcessPriority aPriority) {
 
   MOZ_LOG(mozilla::ipc::gChildProcessLifecycleLog, LogLevel::Info,
           ("REMOTETYPE [childID = %" PRIi32 "] [remoteType = %s]",
-           mSubprocess->GetChildID(), mRemoteType.get()));
+           mSubprocess->GetChildID(), mRemoteType.Stringify().get()));
 
   mLaunchYieldTS = TimeStamp::Now();
   return mSubprocess->AsyncLaunch(std::move(extraArgs));
@@ -2641,13 +2560,9 @@ bool ContentParent::LaunchSubprocessResolve(bool aIsSync,
   return true;
 }
 
-static bool IsFileContent(const nsACString& aRemoteType) {
-  return aRemoteType == FILE_REMOTE_TYPE;
-}
-
-ContentParent::ContentParent(const nsACString& aRemoteType)
+ContentParent::ContentParent(const RemoteType& aRemoteType)
     : mSubprocess(new GeckoChildProcessHost(GeckoProcessType_Content,
-                                            IsFileContent(aRemoteType))),
+                                            aRemoteType.IsFile())),
       mLaunchTS(TimeStamp::Now()),
       mLaunchYieldTS(mLaunchTS),
       mIsAPreallocBlocker(false),
@@ -2657,7 +2572,7 @@ ContentParent::ContentParent(const nsACString& aRemoteType)
       mThreadsafeHandle(
           new ThreadsafeContentParentHandle(this, mChildID, mRemoteType)),
       mLifecycleState(LifecycleState::LAUNCHING),
-      mIsForBrowser(!mRemoteType.IsEmpty()),
+      mIsForBrowser(!mRemoteType.IsNotRemote()),
       mCalledClose(false),
       mCalledKillHard(false),
       mCreatedPairedMinidumps(false),
@@ -2676,9 +2591,6 @@ ContentParent::ContentParent(const nsACString& aRemoteType)
       mHangMonitorActor(nullptr) {
   MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
 
-  mRemoteTypeIsolationPrincipal =
-      CreateRemoteTypeIsolationPrincipal(aRemoteType);
-
   // Insert ourselves into the global linked list of ContentParent objects.
   if (!sContentParents) {
     sContentParents = new LinkedList<ContentParent>();
@@ -2996,9 +2908,9 @@ bool ContentParent::InitInternal(ProcessPriority aInitialPriority) {
   // to the message we send to enable the Sandbox (SendStartProcessSandbox)
   // because different remote types require different sandbox privileges.
 
-  (void)SendRemoteType(mRemoteType, mProfile);
+  (void)SendSetRemoteType(mRemoteType, mProfile);
 
-  if (mRemoteType != PREALLOC_REMOTE_TYPE) {
+  if (!mRemoteType.IsPrealloc()) {
     StartRemoteWorkerService();
   }
 
@@ -3108,7 +3020,7 @@ bool ContentParent::InitInternal(ProcessPriority aInitialPriority) {
 #  ifdef XP_LINUX
   if (shouldSandbox) {
     MOZ_ASSERT(!mSandboxBroker);
-    bool isFileProcess = mRemoteType == FILE_REMOTE_TYPE;
+    bool isFileProcess = mRemoteType.IsFile();
     UniquePtr<SandboxBroker::Policy> policy =
         sSandboxBrokerPolicyFactory->GetContentPolicy(Pid(), isFileProcess);
     if (policy) {
@@ -3637,7 +3549,7 @@ mozilla::ipc::IPCResult ContentParent::RecvFirstIdle() {
   if (mIsAPreallocBlocker) {
     MOZ_LOG(ContentParent::GetLog(), LogLevel::Verbose,
             ("RecvFirstIdle id=%p childID=%" PRIu64 ": Removing Blocker for %s",
-             this, (uint64_t)this->ChildID(), mRemoteType.get()));
+             this, (uint64_t)this->ChildID(), mRemoteType.Stringify().get()));
     PreallocatedProcessManager::RemoveBlocker(mRemoteType, this);
     mIsAPreallocBlocker = false;
   }
@@ -3835,7 +3747,7 @@ NS_IMETHODIMP
 ContentParent::GetState(nsIPropertyBag** aResult) {
   auto props = MakeRefPtr<nsHashPropertyBag>();
   props->SetPropertyAsACString(u"remoteTypePrefix"_ns,
-                               RemoteTypePrefix(mRemoteType));
+                               mRemoteType.StringifyKind());
   *aResult = props.forget().downcast<nsIWritablePropertyBag>().take();
   return NS_OK;
 }
@@ -4736,7 +4648,7 @@ mozilla::ipc::IPCResult ContentParent::RecvPExternalHelperAppConstructor(
   // file:// URI coming from any other process.
   if (uri && uri->SchemeIs("file") &&
       StaticPrefs::browser_tabs_remote_separateFileUriProcess() &&
-      GetRemoteType() != FILE_REMOTE_TYPE) {
+      !GetRemoteType().IsFile()) {
     return IPC_FAIL(this, "Non-file process sent a file:// URI.");
   }
 
@@ -6464,17 +6376,14 @@ mozilla::ipc::IPCResult ContentParent::RecvRecordPageLoadEvent(
   }
 
   // Set the process isolation category based on the remote type for Android.
-  const nsDependentCSubstring remoteTypePrefix =
-      RemoteTypePrefix(GetRemoteType());
-
   using namespace mozilla::performance::pageload_event;
   AndroidIsolationCategory isolationCategory;
-  if (remoteTypePrefix == WEB_REMOTE_TYPE) {
+  if (mRemoteType.IsSharedWeb()) {
     isolationCategory = AndroidIsolationCategory::SHARED_WEB;
-  } else if (remoteTypePrefix == FISSION_WEB_REMOTE_TYPE) {
-    isolationCategory = AndroidIsolationCategory::SITE_ISOLATED;
-  } else if (remoteTypePrefix == WITH_COOP_COEP_REMOTE_TYPE) {
+  } else if (mRemoteType.IsWebCoopCoep()) {
     isolationCategory = AndroidIsolationCategory::COOP_ISOLATED;
+  } else if (mRemoteType.IsIsolatedWeb()) {
+    isolationCategory = AndroidIsolationCategory::SITE_ISOLATED;
   } else {
     isolationCategory = AndroidIsolationCategory::OTHER;
   }
@@ -8004,13 +7913,13 @@ NS_IMETHODIMP ContentParent::GetOsPid(int32_t* aOut) {
 }
 
 NS_IMETHODIMP ContentParent::GetRemoteType(nsACString& aRemoteType) {
-  aRemoteType = GetRemoteType();
+  aRemoteType = GetRemoteType().Stringify();
   return NS_OK;
 }
 
 void ContentParent::StartRemoteWorkerService() {
   MOZ_ASSERT(!mRemoteWorkerServiceActor);
-  MOZ_ASSERT(mRemoteType != PREALLOC_REMOTE_TYPE);
+  MOZ_ASSERT(!mRemoteType.IsPrealloc());
 
   Endpoint<PRemoteWorkerServiceChild> childEp;
   mRemoteWorkerServiceActor =
@@ -8234,7 +8143,7 @@ IPCResult ContentParent::RecvKillGPUProcess() {
 }
 #endif
 
-nsCString ThreadsafeContentParentHandle::GetRemoteType() {
+RemoteType ThreadsafeContentParentHandle::GetRemoteType() {
   return mLoadedOrigins->GetRemoteType();
 }
 
diff --git a/dom/ipc/ContentParent.h b/dom/ipc/ContentParent.h
index 1f7b097d0022..9b3645e5dd52 100644
--- a/dom/ipc/ContentParent.h
+++ b/dom/ipc/ContentParent.h
@@ -104,6 +104,7 @@ namespace dom {
 class BrowsingContextGroup;
 class Element;
 class BrowserParent;
+class IPCTabContext;
 class MemoryReport;
 class TabContext;
 class GetFilesHelper;
@@ -168,11 +169,11 @@ class ContentParent final : public PContentParent,
   /** Shut down the content-process machinery. */
   static void ShutDown();
 
-  static uint32_t GetPoolSize(const nsACString& aContentProcessType);
+  static uint32_t GetPoolSize(const RemoteType& aContentProcessType);
 
-  static uint32_t GetMaxProcessCount(const nsACString& aContentProcessType);
+  static uint32_t GetMaxProcessCount(const RemoteType& aContentProcessType);
 
-  static bool IsMaxProcessCountReached(const nsACString& aContentProcessType);
+  static bool IsMaxProcessCountReached(const RemoteType& aContentProcessType);
 
   static void ReleaseCachedProcesses();
 
@@ -218,7 +219,7 @@ class ContentParent final : public PContentParent,
    *                   The returned KeepAlive will be for this BrowserId.
    */
   static UniqueContentParentKeepAlive GetNewOrUsedLaunchingBrowserProcess(
-      const nsACString& aRemoteType, BrowsingContextGroup* aGroup = nullptr,
+      const RemoteType& aRemoteType, BrowsingContextGroup* aGroup = nullptr,
       hal::ProcessPriority aPriority =
           hal::ProcessPriority::PROCESS_PRIORITY_FOREGROUND,
       bool aPreferUsed = false, uint64_t aBrowserId = 0);
@@ -228,7 +229,7 @@ class ContentParent final : public PContentParent,
    * resolves when the process is finished launching.
    */
   static RefPtr<ContentParent::LaunchPromise> GetNewOrUsedBrowserProcessAsync(
-      const nsACString& aRemoteType, BrowsingContextGroup* aGroup = nullptr,
+      const RemoteType& aRemoteType, BrowsingContextGroup* aGroup = nullptr,
       hal::ProcessPriority aPriority =
           hal::ProcessPriority::PROCESS_PRIORITY_FOREGROUND,
       bool aPreferUsed = false, uint64_t aBrowserId = 0);
@@ -238,7 +239,7 @@ class ContentParent final : public PContentParent,
    * until the process process is finished launching before returning.
    */
   static UniqueContentParentKeepAlive GetNewOrUsedBrowserProcess(
-      const nsACString& aRemoteType, BrowsingContextGroup* aGroup = nullptr,
+      const RemoteType& aRemoteType, BrowsingContextGroup* aGroup = nullptr,
       hal::ProcessPriority aPriority =
           hal::ProcessPriority::PROCESS_PRIORITY_FOREGROUND,
       bool aPreferUsed = false, uint64_t aBrowserId = 0);
@@ -276,7 +277,7 @@ class ContentParent final : public PContentParent,
    */
   static already_AddRefed<RemoteBrowser> CreateBrowser(
       const TabContext& aContext, Element* aFrameElement,
-      const nsACString& aRemoteType, BrowsingContext* aBrowsingContext,
+      const RemoteType& aRemoteType, BrowsingContext* aBrowsingContext,
       ContentParent* aOpenerContentParent);
 
   /**
@@ -302,11 +303,11 @@ class ContentParent final : public PContentParent,
   static void BroadcastMediaCodecsSupportedUpdate(
       RemoteMediaIn aLocation, const media::MediaCodecsSupported& aSupported);
 
-  const nsACString& GetRemoteType() const override;
+  const RemoteType& GetRemoteType() const override;
 
   virtual void DoGetRemoteType(nsACString& aRemoteType,
                                ErrorResult& aError) const override {
-    aRemoteType = GetRemoteType();
+    aRemoteType = GetRemoteType().Stringify();
   }
 
   enum CPIteratorPolicy { eLive, eAll };
@@ -752,8 +753,8 @@ class ContentParent final : public PContentParent,
    * removed from this list, but will still be in the sContentParents list for
    * the GetAll/GetAllEvenIfDead APIs.
    */
-  static nsClassHashtable<nsCStringHashKey, nsTArray<ContentParent*>>*
-      sBrowserContentParents;
+  static nsClassHashtable<nsGenericHashKey<RemoteType>,
+                          nsTArray<ContentParent*>>* sBrowserContentParents;
   static mozilla::StaticAutoPtr<LinkedList<ContentParent>> sContentParents;
 
   void AddShutdownBlockers();
@@ -779,7 +780,7 @@ class ContentParent final : public PContentParent,
       const OriginAttributes& aOriginAttributes, bool aUserActivation,
       bool aTextDirectiveUserActivation);
 
-  explicit ContentParent(const nsACString& aRemoteType);
+  explicit ContentParent(const RemoteType& aRemoteType);
 
   // Common implementation of LaunchSubprocess{Sync,Async}.
   // Return `true` in case of success, `false` if launch was
@@ -871,7 +872,7 @@ class ContentParent final : public PContentParent,
    * |aContentProcessType|.
    */
   static nsTArray<ContentParent*>& GetOrCreatePool(
-      const nsACString& aContentProcessType);
+      const RemoteType& aContentProcessType);
 
   mozilla::ipc::IPCResult RecvInitBackground(
       Endpoint<mozilla::ipc::PBackgroundStarterParent>&& aEndpoint);
@@ -1447,9 +1448,6 @@ class ContentParent final : public PContentParent,
                                         ErrorResult& aRv) override;
   mozilla::ipc::IProtocol* AsNativeActor() override { return this; }
 
-  static already_AddRefed<nsIPrincipal> CreateRemoteTypeIsolationPrincipal(
-      const nsACString& aRemoteType);
-
 #ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
   bool IsBlockingShutdown() { return mBlockShutdownCalled; }
 #endif
@@ -1467,7 +1465,7 @@ class ContentParent final : public PContentParent,
  private:
   // Return an existing ContentParent if possible. Otherwise, `nullptr`.
   static UniqueContentParentKeepAlive GetUsedBrowserProcess(
-      const nsACString& aRemoteType, nsTArray<ContentParent*>& aContentParents,
+      const RemoteType& aRemoteType, nsTArray<ContentParent*>& aContentParents,
       uint32_t aMaxContentParents, bool aPreferUsed, ProcessPriority aPriority,
       uint64_t aBrowserId);
 
@@ -1498,9 +1496,8 @@ class ContentParent final : public PContentParent,
 
   bool mIsAPreallocBlocker;  // We called AddBlocker for this ContentParent
 
-  nsCString mRemoteType;
+  RemoteType mRemoteType;
   nsCString mProfile;
-  nsCOMPtr<nsIPrincipal> mRemoteTypeIsolationPrincipal;
 
   ContentParentId mChildID;
   int32_t mGeolocationWatchID;
@@ -1679,9 +1676,9 @@ class ThreadsafeContentParentHandle final {
   ContentParentId ChildID() const { return mChildID; }
 
   // Get the current RemoteType of this ContentParent. Safe to call from any
-  // thread. If the returned RemoteType is PREALLOC_REMOTE_TYPE, it may change
-  // again in the future.
-  nsCString GetRemoteType() MOZ_EXCLUDES(mMutex);
+  // thread. If the returned RemoteType is Prealloc, it may change again in the
+  // future.
+  RemoteType GetRemoteType() MOZ_EXCLUDES(mMutex);
 
   // Try to get a reference to the real `ContentParent` object from this weak
   // reference. This may only be called on the main thread.
@@ -1710,7 +1707,7 @@ class ThreadsafeContentParentHandle final {
 
  private:
   ThreadsafeContentParentHandle(ContentParent* aActor, ContentParentId aChildID,
-                                const nsACString& aRemoteType)
+                                const RemoteType& aRemoteType)
       : mChildID(aChildID),
         mLoadedOrigins(MakeRefPtr<LoadedOriginSet>(aRemoteType)),
         mWeakActor(aActor) {}
@@ -1739,16 +1736,6 @@ class ThreadsafeContentParentHandle final {
   ContentParent* mWeakActor MOZ_GUARDED_BY(sMainThreadCapability);
 };
 
-// This is the C++ version of remoteTypePrefix in E10SUtils.sys.mjs.
-nsDependentCSubstring RemoteTypePrefix(const nsACString& aContentProcessType);
-
-// This is based on isWebRemoteType in E10SUtils.sys.mjs.
-bool IsWebRemoteType(const nsACString& aContentProcessType);
-
-bool IsWebCoopCoepRemoteType(const nsACString& aContentProcessType);
-
-bool IsExtensionRemoteType(const nsACString& aContentProcessType);
-
 inline nsISupports* ToSupports(mozilla::dom::ContentParent* aContentParent) {
   return static_cast<nsIDOMProcessParent*>(aContentParent);
 }
diff --git a/dom/ipc/DOMTypes.ipdlh b/dom/ipc/DOMTypes.ipdlh
index 08618e2dfb4e..fd6337909915 100644
--- a/dom/ipc/DOMTypes.ipdlh
+++ b/dom/ipc/DOMTypes.ipdlh
@@ -62,6 +62,7 @@ using mozilla::dom::ForceMediaDocument from "mozilla/dom/LoadURIOptionsBinding.h
 using mozilla::dom::NavigationHistoryBehavior from "mozilla/dom/NavigationBinding.h";
 [RefCounted] using class mozilla::dom::ipc::StructuredCloneData from "mozilla/dom/ipc/StructuredCloneData.h";
 [RefCounted] using class nsStructuredCloneContainer from "nsStructuredCloneContainer.h";
+using struct mozilla::dom::RemoteType from "mozilla/dom/RemoteType.h";
 
 namespace mozilla {
 namespace dom {
@@ -156,13 +157,13 @@ struct DocShellLoadStateInit
 
   // The provided remote type of the process responsible for causing the load to
   // occur. Validated in the parent process.
-  nsCString TriggeringRemoteType;
+  RemoteType TriggeringRemoteType;
 
   nsString SrcdocData; // useless without sourcedocshell
 
   nsCString? OriginalURIString;
 
-  nsCString? RemoteTypeOverride;
+  RemoteType? RemoteTypeOverride;
 
   LoadingSessionHistoryInfo? loadingSessionHistoryInfo;
 
diff --git a/dom/ipc/InProcessChild.h b/dom/ipc/InProcessChild.h
index 1bb476a16aeb..393f935d22d4 100644
--- a/dom/ipc/InProcessChild.h
+++ b/dom/ipc/InProcessChild.h
@@ -43,7 +43,9 @@ class InProcessChild final : public nsIDOMProcessChild,
   // |nullptr|.
   static IProtocol* ParentActorFor(IProtocol* aActor);
 
-  const nsACString& GetRemoteType() const override { return NOT_REMOTE_TYPE; }
+  const RemoteType& GetRemoteType() const override {
+    return RemoteType::NotRemote();
+  }
 
  protected:
   already_AddRefed<JSActor> InitJSActor(JS::Handle<JSObject*> aMaybeActor,
diff --git a/dom/ipc/InProcessImpl.cpp b/dom/ipc/InProcessImpl.cpp
index 1517ea0dbb40..c0909b31d493 100644
--- a/dom/ipc/InProcessImpl.cpp
+++ b/dom/ipc/InProcessImpl.cpp
@@ -136,7 +136,7 @@ InProcessParent::GetOsPid(int32_t* aOsPid) {
 }
 
 NS_IMETHODIMP InProcessParent::GetRemoteType(nsACString& aRemoteType) {
-  aRemoteType = NOT_REMOTE_TYPE;
+  aRemoteType = dom::RemoteType::NotRemote().Stringify();
   return NS_OK;
 }
 
diff --git a/dom/ipc/InProcessParent.h b/dom/ipc/InProcessParent.h
index 044f53ee9335..3992cb00140e 100644
--- a/dom/ipc/InProcessParent.h
+++ b/dom/ipc/InProcessParent.h
@@ -45,7 +45,9 @@ class InProcessParent final : public nsIDOMProcessParent,
   // |nullptr|.
   static IProtocol* ChildActorFor(IProtocol* aActor);
 
-  const nsACString& GetRemoteType() const override { return NOT_REMOTE_TYPE; };
+  const RemoteType& GetRemoteType() const override {
+    return RemoteType::NotRemote();
+  };
 
  protected:
   already_AddRefed<JSActor> InitJSActor(JS::Handle<JSObject*> aMaybeActor,
diff --git a/dom/ipc/LoadedOriginSet.cpp b/dom/ipc/LoadedOriginSet.cpp
index 3508cdf47cbe..077a487b44db 100644
--- a/dom/ipc/LoadedOriginSet.cpp
+++ b/dom/ipc/LoadedOriginSet.cpp
@@ -9,17 +9,17 @@
 
 namespace mozilla::dom {
 
-LoadedOriginSet::LoadedOriginSet(const nsACString& aRemoteType)
+LoadedOriginSet::LoadedOriginSet(const RemoteType& aRemoteType)
     : mRemoteType(aRemoteType) {}
 
-nsCString LoadedOriginSet::GetRemoteType() {
+RemoteType LoadedOriginSet::GetRemoteType() {
   MutexAutoLock lock(mMutex);
   return mRemoteType;
 }
 
-void LoadedOriginSet::SetRemoteType(const nsACString& aRemoteType) {
+void LoadedOriginSet::SetRemoteType(const RemoteType& aRemoteType) {
   MutexAutoLock lock(mMutex);
-  MOZ_ASSERT(mRemoteType == PREALLOC_REMOTE_TYPE);
+  MOZ_ASSERT(mRemoteType.IsPrealloc());
   mRemoteType = aRemoteType;
 }
 
@@ -90,7 +90,7 @@ LoadedOriginSet::Level LoadedOriginSet::AddInternal(nsIPrincipal* aPrincipal,
 bool LoadedOriginSet::ValidatePrincipal(
     nsIPrincipal* aPrincipal,
     const EnumSet<ValidatePrincipalOptions>& aOptions) {
-  nsCString remoteType = GetRemoteType();
+  RemoteType remoteType = GetRemoteType();
   auto isPrincipalLoaded = [&](nsIPrincipal* prin) {
     // FIXME: Currently we only match site, and ignore OAs. This is consistent
     // with ValidatePrincipal behaviour prior to bug 2055554. In the future, we
diff --git a/dom/ipc/LoadedOriginSet.h b/dom/ipc/LoadedOriginSet.h
index ee2763d80d08..526bc02ed900 100644
--- a/dom/ipc/LoadedOriginSet.h
+++ b/dom/ipc/LoadedOriginSet.h
@@ -32,7 +32,7 @@ class LoadedOriginSet {
  public:
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(LoadedOriginSet)
 
-  explicit LoadedOriginSet(const nsACString& aRemoteType);
+  explicit LoadedOriginSet(const RemoteType& aRemoteType);
 
   enum class Level : uint8_t {
     Unloaded,
@@ -47,10 +47,10 @@ class LoadedOriginSet {
     Full,
   };
 
-  nsCString GetRemoteType();
+  RemoteType GetRemoteType();
 
   // Should only be called by ContentParent or ContentChild.
-  void SetRemoteType(const nsACString& aRemoteType);
+  void SetRemoteType(const RemoteType& aRemoteType);
 
   // Check if this LoadedOriginSet has the given principal.
   bool Has(nsIPrincipal* aPrincipal, Level aThreshold,
@@ -89,7 +89,7 @@ class LoadedOriginSet {
   };
 
   Mutex mMutex{"LoadedOriginSet"};
-  nsCString mRemoteType MOZ_GUARDED_BY(mMutex);
+  RemoteType mRemoteType MOZ_GUARDED_BY(mMutex);
   nsTArray<AttributeBucket> mLoadedOrigins MOZ_GUARDED_BY(mMutex);
 };
 
diff --git a/dom/ipc/PContent.ipdl b/dom/ipc/PContent.ipdl
index fa2c4d1e15bf..7f4644bc8fa2 100644
--- a/dom/ipc/PContent.ipdl
+++ b/dom/ipc/PContent.ipdl
@@ -186,6 +186,7 @@ using mozilla::dom::UserActivation::Modifiers from "mozilla/dom/UserActivation.h
 using nsIClipboard::ClipboardType from "nsIClipboard.h";
 using nsIUrlClassifierFeature::listType from "nsIUrlClassifierFeature.h";
 using mozilla::dom::ReferrerPolicy from "mozilla/dom/ReferrerPolicyBinding.h";
+using struct mozilla::dom::RemoteType from "mozilla/dom/RemoteType.h";
 
 #ifdef MOZ_WMF_CDM
 using nsIOriginStatusEntry from "nsIWindowsMediaFoundationCDMOriginsListService.h";
@@ -830,7 +831,7 @@ child:
     /**
      * Send the remote type associated with the content process.
      */
-    async RemoteType(nsCString aRemoteType, nsCString aProfile);
+    async SetRemoteType(RemoteType aRemoteType, nsCString aProfile);
 
     /**
      * Record an origin which is being loaded in this content process.
diff --git a/dom/ipc/PreallocatedProcessManager.cpp b/dom/ipc/PreallocatedProcessManager.cpp
index e896a1d80f01..e2351d788531 100644
--- a/dom/ipc/PreallocatedProcessManager.cpp
+++ b/dom/ipc/PreallocatedProcessManager.cpp
@@ -38,7 +38,7 @@ class PreallocatedProcessManagerImpl final : public nsIObserver {
   // See comments on PreallocatedProcessManager for these methods.
   void AddBlocker(ContentParent* aParent);
   void RemoveBlocker(ContentParent* aParent);
-  UniqueContentParentKeepAlive Take(const nsACString& aRemoteType);
+  UniqueContentParentKeepAlive Take(const RemoteType& aRemoteType);
   void Erase(ContentParent* aParent);
 
   PreallocatedProcessManagerImpl(const PreallocatedProcessManagerImpl&) =
@@ -189,7 +189,7 @@ void PreallocatedProcessManagerImpl::RereadPrefs() {
 }
 
 UniqueContentParentKeepAlive PreallocatedProcessManagerImpl::Take(
-    const nsACString& aRemoteType) {
+    const RemoteType& aRemoteType) {
   if (!IsEnabled()) {
     return nullptr;
   }
@@ -269,8 +269,8 @@ void PreallocatedProcessManagerImpl::RemoveBlocker(ContentParent* aParent) {
 bool PreallocatedProcessManagerImpl::CanAllocate() {
   return IsEnabled() && sNumBlockers == 0 &&
          mPreallocatedProcesses.Length() < mNumberPreallocs && !IsShutdown() &&
-         (FissionAutostart() ||
-          !ContentParent::IsMaxProcessCountReached(DEFAULT_REMOTE_TYPE));
+         (FissionAutostart() || !ContentParent::IsMaxProcessCountReached(
+                                    RemoteType(RemoteType::Kind::WebContent)));
 }
 
 void PreallocatedProcessManagerImpl::AllocateAfterDelay() {
@@ -383,24 +383,23 @@ bool PreallocatedProcessManager::Enabled() {
 }
 
 /* static */
-void PreallocatedProcessManager::AddBlocker(const nsACString& aRemoteType,
+void PreallocatedProcessManager::AddBlocker(const RemoteType& aRemoteType,
                                             ContentParent* aParent) {
   MOZ_LOG(ContentParent::GetLog(), LogLevel::Debug,
-          ("AddBlocker: %s %p (sNumBlockers=%d)",
-           PromiseFlatCString(aRemoteType).get(), aParent,
-           PreallocatedProcessManagerImpl::sNumBlockers));
+          ("AddBlocker: %s %p (sNumBlockers=%d)", aRemoteType.Stringify().get(),
+           aParent, PreallocatedProcessManagerImpl::sNumBlockers));
   if (auto impl = GetPPMImpl()) {
     impl->AddBlocker(aParent);
   }
 }
 
 /* static */
-void PreallocatedProcessManager::RemoveBlocker(const nsACString& aRemoteType,
+void PreallocatedProcessManager::RemoveBlocker(const RemoteType& aRemoteType,
                                                ContentParent* aParent) {
-  MOZ_LOG(ContentParent::GetLog(), LogLevel::Debug,
-          ("RemoveBlocker: %s %p (sNumBlockers=%d)",
-           PromiseFlatCString(aRemoteType).get(), aParent,
-           PreallocatedProcessManagerImpl::sNumBlockers));
+  MOZ_LOG(
+      ContentParent::GetLog(), LogLevel::Debug,
+      ("RemoveBlocker: %s %p (sNumBlockers=%d)", aRemoteType.Stringify().get(),
+       aParent, PreallocatedProcessManagerImpl::sNumBlockers));
   if (auto impl = GetPPMImpl()) {
     impl->RemoveBlocker(aParent);
   }
@@ -408,7 +407,7 @@ void PreallocatedProcessManager::RemoveBlocker(const nsACString& aRemoteType,
 
 /* static */
 UniqueContentParentKeepAlive PreallocatedProcessManager::Take(
-    const nsACString& aRemoteType) {
+    const RemoteType& aRemoteType) {
   if (auto impl = GetPPMImpl()) {
     return impl->Take(aRemoteType);
   }
diff --git a/dom/ipc/PreallocatedProcessManager.h b/dom/ipc/PreallocatedProcessManager.h
index 438aab5946a3..ffd7fe242ac6 100644
--- a/dom/ipc/PreallocatedProcessManager.h
+++ b/dom/ipc/PreallocatedProcessManager.h
@@ -6,6 +6,7 @@
 #define mozilla_PreallocatedProcessManager_h
 
 #include "base/basictypes.h"
+#include "mozilla/dom/RemoteType.h"
 #include "mozilla/dom/UniqueContentParentKeepAlive.h"
 #include "nsStringFwd.h"
 
@@ -28,6 +29,7 @@ class PreallocatedProcessManagerImpl;
 
 class PreallocatedProcessManager final {
   using ContentParent = mozilla::dom::ContentParent;
+  using RemoteType = mozilla::dom::RemoteType;
   using UniqueContentParentKeepAlive =
       mozilla::dom::UniqueContentParentKeepAlive;
 
@@ -41,8 +43,8 @@ class PreallocatedProcessManager final {
    * background. To avoid that, the PreallocatedProcessManager won't start up
    * any processes while there is a blocker active.
    */
-  static void AddBlocker(const nsACString& aRemoteType, ContentParent* aParent);
-  static void RemoveBlocker(const nsACString& aRemoteType,
+  static void AddBlocker(const RemoteType& aRemoteType, ContentParent* aParent);
+  static void RemoveBlocker(const RemoteType& aRemoteType,
                             ContentParent* aParent);
 
   /**
@@ -52,7 +54,7 @@ class PreallocatedProcessManager final {
    * If we use a preallocated process, it will schedule the start of
    * another on Idle (AllocateOnIdle()).
    */
-  static UniqueContentParentKeepAlive Take(const nsACString& aRemoteType);
+  static UniqueContentParentKeepAlive Take(const RemoteType& aRemoteType);
 
   /**
    * Note that a process was shut down, and should no longer be tracked as a
diff --git a/dom/ipc/ProcessIsolation.cpp b/dom/ipc/ProcessIsolation.cpp
index 465e57ae4bb7..02e397c75ddf 100644
--- a/dom/ipc/ProcessIsolation.cpp
+++ b/dom/ipc/ProcessIsolation.cpp
@@ -121,7 +121,7 @@ struct CommaSeparatedPref {
 CommaSeparatedPref sSeparatedMozillaDomains{
     "browser.tabs.remote.separatedMozillaDomains"_ns};
 
-bool AllowJITForSiteOrigin(const nsACString& aSiteOriginNoSuffix,
+bool AllowJITForSiteOrigin(nsIURI* aSiteOriginURI,
                            WindowGlobalParent* aParentWindow) {
   nsresult rv;
 
@@ -131,32 +131,30 @@ bool AllowJITForSiteOrigin(const nsACString& aSiteOriginNoSuffix,
     return true;
   }
 
-  nsAutoCString topSiteOriginNoSuffix(aSiteOriginNoSuffix);
+  nsCOMPtr<nsIURI> topSiteOriginURI = aSiteOriginURI;
 
   // If this is a subframe then use the principal of the top window.
   if (aParentWindow) {
+    nsAutoCString topSiteOriginNoSuffix;
     rv = aParentWindow->TopWindowContext()
              ->DocumentPrincipal()
              ->GetSiteOriginNoSuffix(topSiteOriginNoSuffix);
-    if (NS_FAILED(rv)) {
-      topSiteOriginNoSuffix = aSiteOriginNoSuffix;
-    }
+    NS_ENSURE_SUCCESS(rv, true);
+
+    rv = NS_NewURI(getter_AddRefs(topSiteOriginURI), topSiteOriginNoSuffix);
+    NS_ENSURE_SUCCESS(rv, true);
   }
 
-  nsCOMPtr<nsIURI> topSite;
-  rv = NS_NewURI(getter_AddRefs(topSite), topSiteOriginNoSuffix);
-  NS_ENSURE_SUCCESS(rv, true);
-
   bool isJitAllowed = true;
-  if (NS_FAILED(
-          policyService->IsAllowedForURI("jit"_ns, topSite, &isJitAllowed))) {
+  if (NS_FAILED(policyService->IsAllowedForURI("jit"_ns, topSiteOriginURI,
+                                               &isJitAllowed))) {
     return true;
   }
 
   if (!isJitAllowed) {
     MOZ_LOG(gProcessIsolationLog, LogLevel::Debug,
             ("JIT is disabled for site %s by enterprise policy",
-             topSiteOriginNoSuffix.get()));
+             topSiteOriginURI->GetSpecOrDefault().get()));
   }
 
   return isJitAllowed;
@@ -426,24 +424,11 @@ static nsAutoCString OriginString(nsIPrincipal* aPrincipal) {
 }
 
 /**
- * Trim the OriginAttributes, and use it to create a OriginSuffix string
- * appropriate to use within a remoteType string.
+ * Helper method for logging origin attributes as a string.
  */
-static nsAutoCString OriginSuffixForRemoteType(OriginAttributes aAttrs,
-                                               bool aDisableJit) {
+static nsAutoCString OriginAttributesString(const OriginAttributes& aAttrs) {
   nsAutoCString originSuffix;
-  aAttrs.StripAttributes(OriginAttributes::STRIP_FIRST_PARTY_DOMAIN |
-                         OriginAttributes::STRIP_PARTITION_KEY);
   aAttrs.CreateSuffix(originSuffix);
-
-  if (aDisableJit) {
-    if (originSuffix.IsEmpty()) {
-      originSuffix = "^"_ns + DISABLE_JIT_REMOTE_TYPE_SUFFIX;
-    } else {
-      originSuffix += "&"_ns + DISABLE_JIT_REMOTE_TYPE_SUFFIX;
-    }
-  }
-
   return originSuffix;
 }
 
@@ -574,35 +559,35 @@ static bool ShouldIsolateSite(nsIPrincipal* aPrincipal,
   }
 }
 
-static Result<nsCString, nsresult> SpecialBehaviorRemoteType(
-    IsolationBehavior aBehavior, const nsACString& aCurrentRemoteType,
+static Result<RemoteType, nsresult> SpecialBehaviorRemoteType(
+    IsolationBehavior aBehavior, const RemoteType& aCurrentRemoteType,
     WindowGlobalParent* aParentWindow, const OriginAttributes& aAttrs) {
   switch (aBehavior) {
     case IsolationBehavior::ForceWebRemoteType:
-      return {SharedWebRemoteType(aAttrs)};
+      return {RemoteType::SharedWeb(aAttrs)};
     case IsolationBehavior::PrivilegedAbout:
       // The privileged about: content process cannot be disabled, as it
       // causes various actors to break.
-      return {PRIVILEGEDABOUT_REMOTE_TYPE};
+      return {RemoteType(RemoteType::Kind::PrivilegedAbout)};
     case IsolationBehavior::Extension:
       if (ExtensionPolicyService::GetSingleton().UseRemoteExtensions()) {
-        return {EXTENSION_REMOTE_TYPE};
+        return {RemoteType(RemoteType::Kind::Extension)};
       }
-      return {NOT_REMOTE_TYPE};
+      return {RemoteType(RemoteType::Kind::NotRemote)};
     case IsolationBehavior::File:
       if (StaticPrefs::browser_tabs_remote_separateFileUriProcess()) {
-        return {FILE_REMOTE_TYPE};
+        return {RemoteType(RemoteType::Kind::File)};
       }
-      return {SharedWebRemoteType(aAttrs)};
+      return {RemoteType::SharedWeb(aAttrs)};
     case IsolationBehavior::PrivilegedMozilla:
-      return {PRIVILEGEDMOZILLA_REMOTE_TYPE};
+      return {RemoteType(RemoteType::Kind::PrivilegedMozilla)};
     case IsolationBehavior::Parent:
-      return {NOT_REMOTE_TYPE};
+      return {RemoteType(RemoteType::Kind::NotRemote)};
     case IsolationBehavior::Anywhere:
-      return {nsCString(aCurrentRemoteType)};
+      return {aCurrentRemoteType};
     case IsolationBehavior::Inherit:
       MOZ_DIAGNOSTIC_ASSERT(aParentWindow);
-      return {nsCString(aParentWindow->GetRemoteType())};
+      return {aParentWindow->GetRemoteType()};
 
     case IsolationBehavior::Error:
       return Err(NS_ERROR_UNEXPECTED);
@@ -613,30 +598,15 @@ static Result<nsCString, nsresult> SpecialBehaviorRemoteType(
   }
 }
 
-enum class WebProcessType {
-  Web,
-  WebIsolated,
-  WebCoopCoep,
-};
-
 }  // namespace
 
-nsCString SharedWebRemoteType(const OriginAttributes& aAttrs,
-                              bool aDisableJit) {
-  nsAutoCString suffix = OriginSuffixForRemoteType(aAttrs, aDisableJit);
-  if (suffix.IsEmpty()) {
-    return WEB_REMOTE_TYPE;
-  }
-  return WEB_REMOTE_TYPE "="_ns + suffix;
-}
-
 Result<NavigationIsolationOptions, nsresult> IsolationOptionsForNavigation(
     CanonicalBrowsingContext* aTopBC, WindowGlobalParent* aParentWindow,
     nsIURI* aChannelCreationURI, nsIChannel* aChannel,
-    const nsACString& aCurrentRemoteType, bool aHasCOOPMismatch,
+    const RemoteType& aCurrentRemoteType, bool aHasCOOPMismatch,
     bool aForNewTab, uint32_t aLoadStateLoadType,
     const Maybe<uint64_t>& aChannelId,
-    const Maybe<nsCString>& aRemoteTypeOverride) {
+    const Maybe<RemoteType>& aRemoteTypeOverride) {
   // Get the final principal, used to select which process to load into.
   nsCOMPtr<nsIPrincipal> resultPrincipal;
   nsresult rv = nsContentUtils::GetSecurityManager()->GetChannelResultPrincipal(
@@ -688,7 +658,7 @@ Result<NavigationIsolationOptions, nsresult> IsolationOptionsForNavigation(
 
     MOZ_LOG(gProcessIsolationLog, LogLevel::Verbose,
             ("using remote type override (%s) for load",
-             aRemoteTypeOverride->get()));
+             aRemoteTypeOverride->Stringify().get()));
     options.mRemoteType = *aRemoteTypeOverride;
     return options;
   }
@@ -781,7 +751,7 @@ Result<NavigationIsolationOptions, nsresult> IsolationOptionsForNavigation(
       // and it's safe for it to end in the parent process, we should finish the
       // load there.
       bool isUIResource = false;
-      if (aCurrentRemoteType.IsEmpty() &&
+      if (aCurrentRemoteType.IsNotRemote() &&
           (aChannelCreationURI->SchemeIs("about") ||
            (NS_SUCCEEDED(NS_URIChainHasFlags(
                 aChannelCreationURI, nsIProtocolHandler::URI_IS_UI_RESOURCE,
@@ -806,7 +776,7 @@ Result<NavigationIsolationOptions, nsresult> IsolationOptionsForNavigation(
   // to some other remote type, make sure we leave the extension's BCG which we
   // may have entered earlier to separate extension and non-extension BCGs from
   // each-other.
-  if (!aParentWindow && aCurrentRemoteType == EXTENSION_REMOTE_TYPE &&
+  if (!aParentWindow && aCurrentRemoteType.IsExtension() &&
       behavior != IsolationBehavior::Extension &&
       behavior != IsolationBehavior::Anywhere) {
     MOZ_LOG(gProcessIsolationLog, LogLevel::Verbose,
@@ -848,7 +818,7 @@ Result<NavigationIsolationOptions, nsresult> IsolationOptionsForNavigation(
       behavior != IsolationBehavior::Parent &&
       (ExtensionPolicyService::GetSingleton().UseRemoteExtensions() ||
        behavior != IsolationBehavior::Extension) &&
-      !aCurrentRemoteType.IsEmpty() &&
+      !aCurrentRemoteType.IsNotRemote() &&
       aTopBC->GetHasLoadedNonInitialDocument() &&
       (aLoadStateLoadType == LOAD_NORMAL ||
        aLoadStateLoadType == LOAD_HISTORY || aLoadStateLoadType == LOAD_LINK ||
@@ -875,7 +845,8 @@ Result<NavigationIsolationOptions, nsresult> IsolationOptionsForNavigation(
         behavior, aCurrentRemoteType, aParentWindow, originAttributes));
 
     if (options.mRemoteType != aCurrentRemoteType &&
-        (options.mRemoteType.IsEmpty() || aCurrentRemoteType.IsEmpty())) {
+        (options.mRemoteType.IsNotRemote() ||
+         aCurrentRemoteType.IsNotRemote())) {
       options.mReplaceBrowsingContext = true;
     }
 
@@ -883,14 +854,15 @@ Result<NavigationIsolationOptions, nsresult> IsolationOptionsForNavigation(
         gProcessIsolationLog, LogLevel::Debug,
         ("Selecting specific remote type (%s) due to a special case isolation "
          "behavior %s",
-         options.mRemoteType.get(), IsolationBehaviorName(behavior)));
+         options.mRemoteType.Stringify().get(),
+         IsolationBehaviorName(behavior)));
     return options;
   }
 
   // At this point we're definitely not going to be loading in the parent
   // process anymore, so we're definitely going to be replacing BrowsingContext
   // if we're in the parent process.
-  if (aCurrentRemoteType.IsEmpty()) {
+  if (aCurrentRemoteType.IsNotRemote()) {
     MOZ_ASSERT(!aParentWindow);
     options.mReplaceBrowsingContext = true;
   }
@@ -909,6 +881,9 @@ Result<NavigationIsolationOptions, nsresult> IsolationOptionsForNavigation(
   nsAutoCString siteOriginNoSuffix;
   MOZ_TRY(resultOrPrecursor->GetSiteOriginNoSuffix(siteOriginNoSuffix));
 
+  nsCOMPtr<nsIURI> siteOriginURI;
+  MOZ_TRY(NS_NewURI(getter_AddRefs(siteOriginURI), siteOriginNoSuffix));
+
   // Check if we've already loaded a document with the given principal in some
   // content process. We want to finish the load in the same process in that
   // case.
@@ -957,12 +932,12 @@ Result<NavigationIsolationOptions, nsresult> IsolationOptionsForNavigation(
 
         // Check if this WindowGlobalParent has the given resultPrincipal, and
         // if it does, we need to load in that process.
-        if (!wgp->GetRemoteType().IsEmpty() &&
+        if (!wgp->GetRemoteType().IsNotRemote() &&
             principalIsSameSite(wgp->DocumentPrincipal())) {
           MOZ_LOG(gProcessIsolationLog, LogLevel::Debug,
                   ("Found existing frame with matching principal "
                    "(remoteType:(%s), origin:%s)",
-                   PromiseFlatCString(wgp->GetRemoteType()).get(),
+                   wgp->GetRemoteType().Stringify().get(),
                    OriginString(wgp->DocumentPrincipal()).get()));
           options.mRemoteType = wgp->GetRemoteType();
           return options;
@@ -974,40 +949,26 @@ Result<NavigationIsolationOptions, nsresult> IsolationOptionsForNavigation(
     }
   }
 
-  bool isJitAllowed = AllowJITForSiteOrigin(siteOriginNoSuffix, aParentWindow);
-  nsAutoCString originSuffix = OriginSuffixForRemoteType(
-      resultOrPrecursor->OriginAttributesRef(), !isJitAllowed);
+  options.mRemoteType = RemoteType::SharedWeb(originAttributes);
 
-  WebProcessType webProcessType = WebProcessType::Web;
-  if (ShouldIsolateSite(resultOrPrecursor, aTopBC->UseRemoteSubframes())) {
-    webProcessType = WebProcessType::WebIsolated;
+  if (!AllowJITForSiteOrigin(siteOriginURI, aParentWindow)) {
+    options.mRemoteType = options.mRemoteType.WithDisableJit(true);
   }
 
-  // Check if we should be cross-origin isolated.
-  if (options.mShouldCrossOriginIsolate) {
-    webProcessType = WebProcessType::WebCoopCoep;
+  if (options.mShouldCrossOriginIsolate ||
+      ShouldIsolateSite(resultOrPrecursor, aTopBC->UseRemoteSubframes())) {
+    options.mRemoteType = options.mRemoteType.WithSiteOrigin(
+        siteOriginNoSuffix, options.mShouldCrossOriginIsolate
+                                ? RemoteType::Kind::WebCoopCoep
+                                : RemoteType::Kind::WebContent);
   }
 
-  switch (webProcessType) {
-    case WebProcessType::Web:
-      options.mRemoteType =
-          SharedWebRemoteType(originAttributes, !isJitAllowed);
-      break;
-    case WebProcessType::WebIsolated:
-      options.mRemoteType =
-          FISSION_WEB_REMOTE_TYPE "="_ns + siteOriginNoSuffix + originSuffix;
-      break;
-    case WebProcessType::WebCoopCoep:
-      options.mRemoteType =
-          WITH_COOP_COEP_REMOTE_TYPE "="_ns + siteOriginNoSuffix + originSuffix;
-      break;
-  }
   return options;
 }
 
 static bool ValidateBehaviorForWorker(IsolationBehavior aBehavior,
-                                      const nsACString& aCurrentRemoteType) {
-  if (aCurrentRemoteType == NOT_REMOTE_TYPE) {
+                                      const RemoteType& aCurrentRemoteType) {
+  if (aCurrentRemoteType.IsNotRemote()) {
     return true;
   }
 
@@ -1031,14 +992,14 @@ static bool ValidateBehaviorForWorker(IsolationBehavior aBehavior,
       return true;
 
     case IsolationBehavior::PrivilegedAbout:
-      return aCurrentRemoteType == PRIVILEGEDABOUT_REMOTE_TYPE;
+      return aCurrentRemoteType.IsPrivilegedAbout();
 
     case IsolationBehavior::File:
       return !StaticPrefs::browser_tabs_remote_separateFileUriProcess() ||
-             aCurrentRemoteType == FILE_REMOTE_TYPE;
+             aCurrentRemoteType.IsFile();
 
     case IsolationBehavior::PrivilegedMozilla:
-      return aCurrentRemoteType == PRIVILEGEDMOZILLA_REMOTE_TYPE;
+      return aCurrentRemoteType.IsPrivilegedMozilla();
 
     case IsolationBehavior::Error:
       break;
@@ -1049,11 +1010,11 @@ static bool ValidateBehaviorForWorker(IsolationBehavior aBehavior,
 
 Result<WorkerIsolationOptions, nsresult> IsolationOptionsForWorker(
     nsIPrincipal* aPrincipal, WorkerKind aWorkerKind,
-    const nsACString& aCurrentRemoteType, bool aUseRemoteSubframes) {
+    const RemoteType& aCurrentRemoteType, bool aUseRemoteSubframes) {
   MOZ_LOG(gProcessIsolationLog, LogLevel::Verbose,
           ("IsolationOptionsForWorker principal:%s, kind:%s, current:%s",
            OriginString(aPrincipal).get(), WorkerKindName(aWorkerKind),
-           PromiseFlatCString(aCurrentRemoteType).get()));
+           aCurrentRemoteType.Stringify().get()));
 
   MOZ_ASSERT(NS_IsMainThread());
   MOZ_RELEASE_ASSERT(
@@ -1083,11 +1044,10 @@ Result<WorkerIsolationOptions, nsresult> IsolationOptionsForWorker(
   // processes. Currently process selection for workers occurs before response
   // headers are available, so we will never select to load a shared worker in a
   // COOP+COEP content process.
-  nsCString preferredRemoteType =
-      SharedWebRemoteType(aPrincipal->OriginAttributesRef());
+  RemoteType preferredRemoteType =
+      RemoteType::SharedWeb(aPrincipal->OriginAttributesRef());
   if (aWorkerKind == WorkerKind::WorkerKindShared &&
-      !StringBeginsWith(aCurrentRemoteType,
-                        WITH_COOP_COEP_REMOTE_TYPE_PREFIX)) {
+      !aCurrentRemoteType.IsWebCoopCoep()) {
     preferredRemoteType = aCurrentRemoteType;
   }
 
@@ -1118,7 +1078,7 @@ Result<WorkerIsolationOptions, nsresult> IsolationOptionsForWorker(
 
     // Only allow system principal shared workers to load within the parent
     // process, and only if that process is responsible for the load.
-    if (preferredRemoteType == NOT_REMOTE_TYPE) {
+    if (preferredRemoteType.IsNotRemote()) {
       MOZ_LOG(gProcessIsolationLog, LogLevel::Debug,
               ("Loading system principal shared worker in parent process"));
       behavior = IsolationBehavior::Parent;
@@ -1132,7 +1092,7 @@ Result<WorkerIsolationOptions, nsresult> IsolationOptionsForWorker(
     MOZ_ASSERT(resultOrPrecursor->GetIsNullPrincipal());
     MOZ_ASSERT(aWorkerKind == WorkerKindShared);
 
-    if (preferredRemoteType == NOT_REMOTE_TYPE) {
+    if (preferredRemoteType.IsNotRemote()) {
       MOZ_LOG(gProcessIsolationLog, LogLevel::Debug,
               ("Ensuring precursorless null principal shared worker loads in a "
                "content process"));
@@ -1141,7 +1101,7 @@ Result<WorkerIsolationOptions, nsresult> IsolationOptionsForWorker(
       MOZ_LOG(gProcessIsolationLog, LogLevel::Debug,
               ("Loading precursorless null principal shared worker within "
                "current remotetype: (%s)",
-               preferredRemoteType.get()));
+               preferredRemoteType.Stringify().get()));
       behavior = IsolationBehavior::Anywhere;
     }
   }
@@ -1158,7 +1118,7 @@ Result<WorkerIsolationOptions, nsresult> IsolationOptionsForWorker(
         gProcessIsolationLog, LogLevel::Warning,
         ("Rejecting invalid worker isolation behavior %s for remote type %s",
          IsolationBehaviorName(behavior),
-         PromiseFlatCString(aCurrentRemoteType).get()));
+         aCurrentRemoteType.Stringify().get()));
     return Err(NS_ERROR_FAILURE);
   }
 
@@ -1171,7 +1131,7 @@ Result<WorkerIsolationOptions, nsresult> IsolationOptionsForWorker(
         gProcessIsolationLog, LogLevel::Debug,
         ("Selecting specific %s worker remote type (%s) due to a special case "
          "isolation behavior %s",
-         WorkerKindName(aWorkerKind), options.mRemoteType.get(),
+         WorkerKindName(aWorkerKind), options.mRemoteType.Stringify().get(),
          IsolationBehaviorName(behavior)));
     return options;
   }
@@ -1179,30 +1139,29 @@ Result<WorkerIsolationOptions, nsresult> IsolationOptionsForWorker(
   nsAutoCString siteOriginNoSuffix;
   MOZ_TRY(resultOrPrecursor->GetSiteOriginNoSuffix(siteOriginNoSuffix));
 
-  bool isJitAllowed = AllowJITForSiteOrigin(siteOriginNoSuffix, nullptr);
+  nsCOMPtr<nsIURI> siteOriginURI;
+  MOZ_TRY(NS_NewURI(getter_AddRefs(siteOriginURI), siteOriginNoSuffix));
+
+  options.mRemoteType =
+      RemoteType::SharedWeb(resultOrPrecursor->OriginAttributesRef());
+
+  if (!AllowJITForSiteOrigin(siteOriginURI, nullptr)) {
+    options.mRemoteType = options.mRemoteType.WithDisableJit(true);
+  }
 
   // If we should be isolating this site, we can determine the correct fission
   // remote type from the principal's site-origin.
   if (ShouldIsolateSite(resultOrPrecursor, aUseRemoteSubframes)) {
-    nsAutoCString originSuffix = OriginSuffixForRemoteType(
-        resultOrPrecursor->OriginAttributesRef(), !isJitAllowed);
-
-    nsCString prefix = aWorkerKind == WorkerKindService
-                           ? SERVICEWORKER_REMOTE_TYPE
-                           : FISSION_WEB_REMOTE_TYPE;
-    options.mRemoteType = prefix + "="_ns + siteOriginNoSuffix + originSuffix;
-
-    MOZ_LOG(gProcessIsolationLog, LogLevel::Debug,
-            ("Isolating web content %s worker in remote type (%s)",
-             WorkerKindName(aWorkerKind), options.mRemoteType.get()));
-  } else {
-    options.mRemoteType = SharedWebRemoteType(
-        resultOrPrecursor->OriginAttributesRef(), !isJitAllowed);
-
-    MOZ_LOG(gProcessIsolationLog, LogLevel::Debug,
-            ("Loading web content %s worker in shared web remote type",
-             WorkerKindName(aWorkerKind)));
+    options.mRemoteType = options.mRemoteType.WithSiteOrigin(
+        siteOriginNoSuffix, aWorkerKind == WorkerKindService
+                                ? RemoteType::Kind::WebServiceWorker
+                                : RemoteType::Kind::WebContent);
   }
+
+  MOZ_LOG(gProcessIsolationLog, LogLevel::Debug,
+          ("Loading web content %s worker in remote type (%s)",
+           WorkerKindName(aWorkerKind), options.mRemoteType.Stringify().get()));
+
   return options;
 }
 
@@ -1297,16 +1256,15 @@ static already_AddRefed<nsIURI> MaybeResolveWebAppHandler(nsIURI* aURI) {
   return newURI.forget();
 }
 
-Result<nsCString, nsresult> PredictRemoteTypeForURI(
+Result<RemoteType, nsresult> PredictRemoteTypeForURI(
     nsIURI* aURI, const OriginAttributes& aOriginAttributes,
-    const nsACString& aPreferredRemoteType, bool aUseRemoteSubframes) {
-  MOZ_LOG(gProcessIsolationLog, LogLevel::Verbose,
-          ("PredictRemoteTypeForURI uri:%s, preferred:%s, oa:%s, "
-           "useRemoteSubframes:%d",
-           aURI->GetSpecOrDefault().get(),
-           PromiseFlatCString(aPreferredRemoteType).get(),
-           OriginSuffixForRemoteType(aOriginAttributes, false).get(),
-           aUseRemoteSubframes));
+    const RemoteType& aPreferredRemoteType, bool aUseRemoteSubframes) {
+  MOZ_LOG(
+      gProcessIsolationLog, LogLevel::Verbose,
+      ("PredictRemoteTypeForURI uri:%s, preferred:%s, oa:%s, "
+       "useRemoteSubframes:%d",
+       aURI->GetSpecOrDefault().get(), aPreferredRemoteType.Stringify().get(),
+       OriginAttributesString(aOriginAttributes).get(), aUseRemoteSubframes));
 
   IsolationBehavior behavior = IsolationBehaviorForURI(
       aURI, /* aIsSubframe */ false, /* aForChannelCreationURI */ true,
@@ -1372,13 +1330,13 @@ Result<nsCString, nsresult> PredictRemoteTypeForURI(
 
   // If we have a special behaviour RemoteType, return it.
   if (behavior != IsolationBehavior::WebContent) {
-    nsCString remoteType = MOZ_TRY(SpecialBehaviorRemoteType(
+    RemoteType remoteType = MOZ_TRY(SpecialBehaviorRemoteType(
         behavior, aPreferredRemoteType, nullptr, aOriginAttributes));
 
     MOZ_LOG(gProcessIsolationLog, LogLevel::Debug,
             ("Predicting specific remote type (%s) due to a special case "
              "isolation behavior %s",
-             remoteType.get(), IsolationBehaviorName(behavior)));
+             remoteType.Stringify().get(), IsolationBehaviorName(behavior)));
     return remoteType;
   }
 
@@ -1387,35 +1345,36 @@ Result<nsCString, nsresult> PredictRemoteTypeForURI(
   nsAutoCString siteOriginNoSuffix;
   MOZ_TRY(principal->GetSiteOriginNoSuffix(siteOriginNoSuffix));
 
-  bool isJitAllowed = AllowJITForSiteOrigin(siteOriginNoSuffix, nullptr);
-  nsAutoCString originSuffix = OriginSuffixForRemoteType(
-      principal->OriginAttributesRef(), !isJitAllowed);
+  nsCOMPtr<nsIURI> siteOriginURI;
+  MOZ_TRY(NS_NewURI(getter_AddRefs(siteOriginURI), siteOriginNoSuffix));
+
+  RemoteType remoteType = RemoteType::SharedWeb(aOriginAttributes);
+
+  if (!AllowJITForSiteOrigin(siteOriginURI, nullptr)) {
+    remoteType = remoteType.WithDisableJit(true);
+  }
 
   // The only situation we'll return a coop+coep remote type is if the preferred
   // remote type would perfectly match. Check if that is the case.
-  if (StringBeginsWith(aPreferredRemoteType,
-                       WITH_COOP_COEP_REMOTE_TYPE_PREFIX)) {
-    nsCString coopCoepRemoteType =
-        WITH_COOP_COEP_REMOTE_TYPE "="_ns + siteOriginNoSuffix + originSuffix;
+  if (aPreferredRemoteType.IsWebCoopCoep()) {
+    RemoteType coopCoepRemoteType = remoteType.WithSiteOrigin(
+        siteOriginNoSuffix, RemoteType::Kind::WebCoopCoep);
     if (coopCoepRemoteType == aPreferredRemoteType) {
       MOZ_LOG(gProcessIsolationLog, LogLevel::Verbose,
               ("Predicting preferred COOP+COEP remote type (%s) due to "
                "compatible site-origin %s",
-               coopCoepRemoteType.get(), OriginString(principal).get()));
+               coopCoepRemoteType.Stringify().get(),
+               OriginString(principal).get()));
       return coopCoepRemoteType;
     }
   }
 
-  nsCString remoteType;
   if (ShouldIsolateSite(principal, aUseRemoteSubframes)) {
-    remoteType =
-        FISSION_WEB_REMOTE_TYPE "="_ns + siteOriginNoSuffix + originSuffix;
-  } else {
-    remoteType = SharedWebRemoteType(aOriginAttributes, !isJitAllowed);
+    remoteType = remoteType.WithSiteOrigin(siteOriginNoSuffix);
   }
 
   MOZ_LOG(gProcessIsolationLog, LogLevel::Verbose,
-          ("Predicting web remote type (%s)", remoteType.get()));
+          ("Predicting web remote type (%s)", remoteType.Stringify().get()));
   return remoteType;
 }
 
@@ -1497,7 +1456,7 @@ bool IsIsolateHighValueSiteEnabled() {
 }
 
 bool ValidatePrincipalCouldPotentiallyBeLoadedBy(
-    nsIPrincipal* aPrincipal, const nsACString& aRemoteType,
+    nsIPrincipal* aPrincipal, const RemoteType& aRemoteType,
     const EnumSet<ValidatePrincipalOptions>& aOptions,
     FunctionRef<bool(nsIPrincipal*)> aIsPrincipalLoaded) {
 #ifdef DEBUG
@@ -1514,7 +1473,7 @@ bool ValidatePrincipalCouldPotentiallyBeLoadedBy(
 #endif
 
   // Don't bother validating principals from the parent process.
-  if (aRemoteType == NOT_REMOTE_TYPE) {
+  if (aRemoteType.IsNotRemote()) {
     return true;
   }
 
@@ -1610,7 +1569,7 @@ bool ValidatePrincipalCouldPotentiallyBeLoadedBy(
     if (!StaticPrefs::browser_tabs_remote_separateFileUriProcess()) {
       return true;
     }
-    return aRemoteType == FILE_REMOTE_TYPE;
+    return aRemoteType.IsFile();
   }
 
   if (originScheme == "about"_ns) {
@@ -1642,11 +1601,11 @@ bool ValidatePrincipalCouldPotentiallyBeLoadedBy(
         // unfortunately not part of the principal.
         return true;
       case IsolationBehavior::Extension:
-        return aRemoteType == EXTENSION_REMOTE_TYPE;
+        return aRemoteType.IsExtension();
       case IsolationBehavior::PrivilegedAbout:
-        return aRemoteType == PRIVILEGEDABOUT_REMOTE_TYPE;
+        return aRemoteType.IsPrivilegedAbout();
       case IsolationBehavior::ForceWebRemoteType:
-        return RemoteTypePrefix(aRemoteType) == WEB_REMOTE_TYPE;
+        return aRemoteType.IsSharedWeb();
       case IsolationBehavior::WebContent:
       case IsolationBehavior::Error:
         // NOTE: We can encounter races around about: pages being unregistered.
@@ -1658,22 +1617,9 @@ bool ValidatePrincipalCouldPotentiallyBeLoadedBy(
     }
   }
 
-  // If the remote type doesn't have an origin suffix, we can do no further
-  // principal validation with it.
-  int32_t equalIdx = aRemoteType.FindChar('=');
-  if (equalIdx == kNotFound) {
-    return true;
-  }
-
-  // Split out the remote type prefix and the origin suffix.
-  nsDependentCSubstring typePrefix(aRemoteType, 0, equalIdx);
-  nsDependentCSubstring typeOrigin(aRemoteType, equalIdx + 1);
-
-  // Only validate webIsolated, webCOOP+COEP and webServiceWorker remote types
-  // for now. This should be expanded in the future.
-  if (typePrefix != FISSION_WEB_REMOTE_TYPE &&
-      typePrefix != WITH_COOP_COEP_REMOTE_TYPE &&
-      typePrefix != SERVICEWORKER_REMOTE_TYPE) {
+  // Only validate webIsolated and webServiceWorker remote types for now. This
+  // should be expanded in the future.
+  if (!aRemoteType.IsIsolatedWeb()) {
     return true;
   }
 
@@ -1682,29 +1628,21 @@ bool ValidatePrincipalCouldPotentiallyBeLoadedBy(
   // HACK: Unfortunately, we can't easily check useRemoteSubframes here, but we
   // shouldn't be loading any webCOOP+COEP windows without useRemoteSubframes if
   // Fission is enabled.
-  if (typePrefix == WITH_COOP_COEP_REMOTE_TYPE &&
-      !mozilla::FissionAutostart()) {
-    return true;
-  }
-
-  // Trim any OriginAttributes from the origin, as those will not be validated.
-  int32_t suffixIdx = typeOrigin.RFindChar('^');
-  nsDependentCSubstring typeOriginNoSuffix(typeOrigin, 0, suffixIdx);
-
-  // If the origin perfectly matches, we can skip computing the site origin.
-  if (typeOriginNoSuffix == originNoSuffix) {
+  if (aRemoteType.IsWebCoopCoep() && !mozilla::FissionAutostart()) {
     return true;
   }
 
   // NOTE: Currently every webIsolated remote type is site-origin keyed, meaning
-  // we can unconditionally compare site origins. If this changes in the future,
-  // this logic will need to be updated to reflect that.
+  // we can unconditionally compare site origin to the origin from the
+  // remoteType. If this changes in the future, this logic will need to be
+  // updated to reflect that.
   nsAutoCString siteOriginNoSuffix;
   if (NS_FAILED(aPrincipal->GetSiteOriginNoSuffix(siteOriginNoSuffix))) {
     MOZ_ASSERT_UNREACHABLE("Failed when not late in shutdown?");
     return false;
   }
-  return siteOriginNoSuffix == typeOriginNoSuffix;
+
+  return aRemoteType.OriginNoSuffix() == siteOriginNoSuffix;
 }
 
 }  // namespace mozilla::dom
diff --git a/dom/ipc/ProcessIsolation.h b/dom/ipc/ProcessIsolation.h
index c35800918142..f6117615c6ac 100644
--- a/dom/ipc/ProcessIsolation.h
+++ b/dom/ipc/ProcessIsolation.h
@@ -28,17 +28,10 @@ constexpr nsLiteralCString kHighValueHasSavedLoginPermission =
 constexpr nsLiteralCString kHighValueIsLoggedInPermission =
     "highValueIsLoggedIn"_ns;
 
-/**
- * Given a specific set of BrowsingContext origin attributes, get a shared "web"
- * process which should be used for loading shared content.
- */
-nsCString SharedWebRemoteType(const OriginAttributes& aAttrs,
-                              bool aDisableJit = false);
-
 // NavigationIsolationOptions is passed through the methods to store the state
 // of the possible process and/or browsing context change.
 struct NavigationIsolationOptions {
-  nsCString mRemoteType;
+  RemoteType mRemoteType;
   bool mReplaceBrowsingContext = false;
   uint64_t mSpecificGroupId = 0;
   bool mShouldCrossOriginIsolate = false;
@@ -61,15 +54,15 @@ struct NavigationIsolationOptions {
 Result<NavigationIsolationOptions, nsresult> IsolationOptionsForNavigation(
     CanonicalBrowsingContext* aTopBC, WindowGlobalParent* aParentWindow,
     nsIURI* aChannelCreationURI, nsIChannel* aChannel,
-    const nsACString& aCurrentRemoteType, bool aHasCOOPMismatch,
+    const RemoteType& aCurrentRemoteType, bool aHasCOOPMismatch,
     bool aForNewTab, uint32_t aLoadStateLoadType,
     const Maybe<uint64_t>& aChannelId,
-    const Maybe<nsCString>& aRemoteTypeOverride);
+    const Maybe<RemoteType>& aRemoteTypeOverride);
 
 // WorkerIsolationOptions is passed back to the RemoteWorkerManager to store the
 // destination process information for remote worker loads.
 struct WorkerIsolationOptions {
-  nsCString mRemoteType;
+  RemoteType mRemoteType;
 };
 
 /**
@@ -80,7 +73,7 @@ struct WorkerIsolationOptions {
  */
 Result<WorkerIsolationOptions, nsresult> IsolationOptionsForWorker(
     nsIPrincipal* aPrincipal, WorkerKind aWorkerKind,
-    const nsACString& aCurrentRemoteType, bool aUseRemoteSubframes);
+    const RemoteType& aCurrentRemoteType, bool aUseRemoteSubframes);
 
 /**
  * Given a URI being loaded, and some relevant context, predict what remote type
@@ -92,9 +85,9 @@ Result<WorkerIsolationOptions, nsresult> IsolationOptionsForWorker(
  * frontend JS, and should not be used as part of navigation. The remote types
  * selected by this method are not used to enforce security invariants.
  */
-Result<nsCString, nsresult> PredictRemoteTypeForURI(
+Result<RemoteType, nsresult> PredictRemoteTypeForURI(
     nsIURI* aURI, const OriginAttributes& aOriginAttributes,
-    const nsACString& aPreferredRemoteType, bool aUseRemoteSubframes);
+    const RemoteType& aPreferredRemoteType, bool aUseRemoteSubframes);
 
 /**
  * Adds a `highValue` permission to the permissions database, and make loads of
@@ -169,7 +162,7 @@ enum class ValidatePrincipalOptions {
  * assertions, and should NOT be used for process isolation decisions.
  */
 bool ValidatePrincipalCouldPotentiallyBeLoadedBy(
-    nsIPrincipal* aPrincipal, const nsACString& aRemoteType,
+    nsIPrincipal* aPrincipal, const RemoteType& aRemoteType,
     const EnumSet<ValidatePrincipalOptions>& aOptions,
     FunctionRef<bool(nsIPrincipal*)> aIsPrincipalLoaded = nullptr);
 
diff --git a/dom/ipc/ProcessPriorityManager.cpp b/dom/ipc/ProcessPriorityManager.cpp
index 5c2705dd7f8a..022186720d8a 100644
--- a/dom/ipc/ProcessPriorityManager.cpp
+++ b/dom/ipc/ProcessPriorityManager.cpp
@@ -748,7 +748,7 @@ ProcessPriority ParticularProcessPriorityManager::CurrentPriority() {
 
 ProcessPriority ParticularProcessPriorityManager::ComputePriority() {
   if (!mHighPriorityBrowserParents.IsEmpty() ||
-      mContentParent->GetRemoteType() == EXTENSION_REMOTE_TYPE ||
+      mContentParent->GetRemoteType().IsExtension() ||
       mHoldsPlayingAudioWakeLock) {
     return PROCESS_PRIORITY_FOREGROUND;
   }
diff --git a/dom/ipc/RemoteType.cpp b/dom/ipc/RemoteType.cpp
new file mode 100644
index 000000000000..08fe26206506
--- /dev/null
+++ b/dom/ipc/RemoteType.cpp
@@ -0,0 +1,401 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/RemoteType.h"
+
+#include "OriginAttributes.h"
+#include "ipc/IPCMessageUtilsSpecializations.h"
+#include "mozilla/BasePrincipal.h"
+#include "mozilla/NeverDestroyed.h"
+#include "nsIURI.h"
+#include "nsNetUtil.h"
+#include "nsPrintfCString.h"
+#include "nsURLHelper.h"
+
+namespace mozilla::dom {
+
+// URLParams value used to indicate a boolean 'true' value.
+// The lack of the attribute is used to indicate 'false'.
+static constexpr nsLiteralCString kRemoteTypeAttrTrue = "1"_ns;
+
+/* static */
+const RemoteType& RemoteType::NotRemote() {
+  static NeverDestroyed<RemoteType> sNotRemote(Kind::NotRemote);
+  return *sNotRemote;
+}
+
+/* static */
+RemoteType RemoteType::SharedWeb(const OriginAttributes& aAttrs) {
+  RemoteType type(Kind::WebContent);
+  type.mUserContextId = aAttrs.mUserContextId;
+  type.mPrivateBrowsingId = aAttrs.mPrivateBrowsingId;
+  type.mGeckoViewSessionContextId = aAttrs.mGeckoViewSessionContextId;
+  MOZ_ASSERT(type.CheckValidity());
+  return type;
+}
+
+RemoteType::RemoteType() = default;
+RemoteType::~RemoteType() = default;
+
+RemoteType::RemoteType(RemoteType::Kind aKind) : mKind(aKind) {
+  MOZ_RELEASE_ASSERT(CheckValidity());
+}
+
+RemoteType::RemoteType(const RemoteType&) = default;
+RemoteType& RemoteType::operator=(const RemoteType&) = default;
+
+bool RemoteType::operator==(const RemoteType& aOther) const {
+  bool isEqual =
+      mKind == aOther.mKind && mOriginNoSuffix == aOther.mOriginNoSuffix &&
+      std::apply(
+          [&, this](auto&&... aAttrs) -> bool {
+            return ((this->*aAttrs.mMember == aOther.*aAttrs.mMember) && ...);
+          },
+          kAttrs);
+  // Sanity checks to catch if someone misses a flag in one of the methods.
+  MOZ_ASSERT_IF(isEqual, Hash() == aOther.Hash());
+  MOZ_ASSERT_IF(isEqual, Stringify() == aOther.Stringify());
+  return isEqual;
+}
+
+// We can directly add integers & enums to the hash, but need to call HashString
+// before adding strings to the hash.
+template <typename T>
+static auto PreHashAttr(const T& aValue) {
+  if constexpr (std::is_integral_v<T> || std::is_enum_v<T>) {
+    return aValue;
+  } else {
+    return HashString(aValue);
+  }
+}
+
+HashNumber RemoteType::Hash() const {
+  return std::apply(
+      [&, this](auto&&... aAttrs) -> HashNumber {
+        return HashGeneric(PreHashAttr(mKind), HashString(mOriginNoSuffix),
+                           PreHashAttr(this->*aAttrs.mMember)...);
+      },
+      kAttrs);
+}
+
+// NOTE: This specifically parses the "kind" part of the remote type string,
+// rather than the value returned from `StringifyKind`. This is only relevant
+// for `NotRemote`, which uses "parent" for `StringifyKind`, but VoidCString()
+// for `Stringify`.
+//
+// FIXME: We should make this more aligned by changing the representation of
+// `NotRemote` to "parent" (bug 1508757)
+static RemoteType::Kind ParseKind(const nsACString& aKindStr) {
+  if (aKindStr.IsVoid()) {
+    return RemoteType::Kind::NotRemote;
+  }
+  if (aKindStr == "prealloc"_ns) {
+    return RemoteType::Kind::Prealloc;
+  }
+  // NOTE: The 'webIsolated' and 'web' prefixes are interpreted the same, and
+  // generated based on the presence of a URL in ToString() to maintain
+  // a level of backwards compatibility with tests assuming the old format.
+  if (aKindStr == "web"_ns || aKindStr == "webIsolated"_ns) {
+    return RemoteType::Kind::WebContent;
+  }
+  if (aKindStr == "webCOOP+COEP") {
+    return RemoteType::Kind::WebCoopCoep;
+  }
+  if (aKindStr == "webServiceWorker") {
+    return RemoteType::Kind::WebServiceWorker;
+  }
+  if (aKindStr == "file"_ns) {
+    return RemoteType::Kind::File;
+  }
+  if (aKindStr == "privilegedabout"_ns) {
+    return RemoteType::Kind::PrivilegedAbout;
+  }
+  if (aKindStr == "privilegedmozilla"_ns) {
+    return RemoteType::Kind::PrivilegedMozilla;
+  }
+  if (aKindStr == "extension"_ns) {
+    return RemoteType::Kind::Extension;
+  }
+  if (aKindStr == "inference"_ns) {
+    return RemoteType::Kind::Inference;
+  }
+  return RemoteType::Kind::Unknown;
+}
+
+static bool ParseAttr(const nsACString& aValue, bool& aMember) {
+  aMember = true;
+  return aValue == kRemoteTypeAttrTrue;
+}
+
+static bool ParseAttr(const nsACString& aValue, uint32_t& aMember) {
+  nsresult rv = NS_OK;
+  aMember = aValue.ToInteger(&rv);
+  return NS_SUCCEEDED(rv);
+}
+
+static bool ParseAttr(const nsACString& aValue, nsString& aMember) {
+  aMember = NS_ConvertUTF8toUTF16(aValue);
+  return true;
+}
+
+/* static */ RemoteType RemoteType::ParseNoValidityCheck(
+    const nsACString& aRemoteType) {
+  RemoteType type;
+
+  int32_t equalIdx = aRemoteType.FindChar('=');
+  if (equalIdx == kNotFound) {
+    type.mKind = ParseKind(aRemoteType);
+    return type;
+  }
+
+  type.mKind = ParseKind(Substring(aRemoteType, 0, equalIdx));
+  nsDependentCSubstring site(aRemoteType, equalIdx + 1);
+
+  int32_t caretIdx = site.RFindChar('^');
+  if (caretIdx != kNotFound) {
+    bool ok = URLParams::Parse(
+        Substring(site, caretIdx + 1), true,
+        [&](const nsACString& aName, const nsACString& aValue) {
+          return std::apply(
+              [&](auto&&... aAttrs) {
+                return ((aName == aAttrs.mName &&
+                         ParseAttr(aValue, type.*aAttrs.mMember)) ||
+                        ...);
+              },
+              kAttrs);
+        });
+    NS_ENSURE_TRUE(ok, RemoteType{});
+    type.mOriginNoSuffix = Substring(site, 0, caretIdx);
+  } else {
+    type.mOriginNoSuffix = site;
+  }
+  return type;
+}
+
+/* static */ RemoteType RemoteType::Parse(const nsACString& aRemoteType) {
+  RemoteType type = ParseNoValidityCheck(aRemoteType);
+
+  // Ensure the type parsed to a valid RemoteType, as we never want to expose an
+  // non-Unknown but invalid RemoteType outside of this .cpp file.
+  NS_ENSURE_TRUE(type.CheckValidity(), RemoteType{});
+
+  // Ensure the string representation of the remote type matches aRemoteType.
+  // This is much stricter than e.g. principal or OriginAttributes parsing, but
+  // we shouldn't be storing RemoteType instances in the profile, so it should
+  // be OK to be strict here.
+  NS_ENSURE_TRUE(type.Stringify() == aRemoteType, RemoteType{});
+  return type;
+}
+
+nsCString RemoteType::StringifyKind() const {
+  MOZ_ASSERT(CheckValidity());
+  switch (mKind) {
+    case RemoteType::Kind::NotRemote:
+      // NOTE: Unlike other remote types, the full RemoteType string for
+      // NotRemote is VoidCString(). We hope to change this in bug 1508757.
+      return "parent"_ns;
+    case RemoteType::Kind::Prealloc:
+      return "prealloc"_ns;
+    case RemoteType::Kind::WebContent:
+      // NOTE: See the comment in ParseKind for why we do this.
+      return HasOrigin() ? "webIsolated"_ns : "web"_ns;
+    case RemoteType::Kind::WebCoopCoep:
+      return "webCOOP+COEP"_ns;
+    case RemoteType::Kind::WebServiceWorker:
+      return "webServiceWorker"_ns;
+    case RemoteType::Kind::File:
+      return "file"_ns;
+    case RemoteType::Kind::PrivilegedAbout:
+      return "privilegedabout"_ns;
+    case RemoteType::Kind::PrivilegedMozilla:
+      return "privilegedmozilla"_ns;
+    case RemoteType::Kind::Extension:
+      return "extension"_ns;
+    case RemoteType::Kind::Inference:
+      return "inference"_ns;
+    case RemoteType::Kind::Unknown:
+      // This is not a valid remote type, but we return a string here to avoid
+      // crashes in logs if an unknown remote type is printed.
+      return "<unknown>"_ns;
+    default:
+      MOZ_CRASH("Unsupported Kind in StringifyKind");
+  }
+}
+
+static void SetAttr(URLParams& aParam, const nsACString& aName,
+                    const bool& aMember) {
+  if (aMember) {
+    aParam.Set(aName, kRemoteTypeAttrTrue);
+  }
+}
+
+static void SetAttr(URLParams& aParam, const nsACString& aName,
+                    const uint32_t& aMember) {
+  if (aMember != 0) {
+    aParam.Set(aName, nsPrintfCString("%" PRIu32, aMember));
+  }
+}
+
+static void SetAttr(URLParams& aParam, const nsACString& aName,
+                    const nsString& aMember) {
+  if (!aMember.IsEmpty()) {
+    aParam.Set(aName, NS_ConvertUTF16toUTF8(aMember));
+  }
+}
+
+nsAutoCString RemoteType::StringifyMeta() const {
+  MOZ_ASSERT(CheckValidity());
+
+  nsAutoCString meta(mOriginNoSuffix);
+
+  if (HasAttrs()) {
+    URLParams params;
+    std::apply(
+        [&, this](auto&&... aAttrs) {
+          (SetAttr(params, aAttrs.mName, this->*aAttrs.mMember), ...);
+        },
+        kAttrs);
+
+    nsAutoCString paramsStr;
+    params.Serialize(paramsStr, /* encode */ true);
+
+    meta += "^"_ns + paramsStr;
+  }
+
+  return meta;
+}
+
+nsCString RemoteType::Stringify() const {
+  MOZ_ASSERT(CheckValidity());
+
+  // FIXME: We should change the representation of not-remote! (bug 1508757)
+  if (IsNotRemote()) {
+    return VoidCString();
+  }
+
+  nsCString kindStr = StringifyKind();
+  if (HasMeta()) {
+    kindStr += "="_ns + StringifyMeta();
+  }
+
+  return kindStr;
+}
+
+static bool AttrIsSet(const bool& aValue) { return aValue; }
+static bool AttrIsSet(const uint32_t& aValue) { return aValue != 0; }
+static bool AttrIsSet(const nsString& aValue) { return !aValue.IsEmpty(); }
+
+bool RemoteType::HasAttrs() const {
+  return std::apply(
+      [this](auto&&... aArgs) {
+        return (AttrIsSet(this->*aArgs.mMember) || ...);
+      },
+      kAttrs);
+}
+
+bool RemoteType::CheckValidity() const {
+  // If we don't have a WebContent kind, no extra fields can be used.
+  if (!IsWeb() && HasMeta()) {
+    NS_WARNING("Invalid RemoteType: Non-web type has metadata");
+    return false;
+  }
+
+  if (HasOrigin()) {
+    nsCOMPtr<nsIURI> uri;
+    if (NS_FAILED(NS_NewURI(getter_AddRefs(uri), mOriginNoSuffix))) {
+      NS_WARNING("Invalid RemoteType: Invalid OriginNoSuffix URI");
+      return false;
+    }
+
+    nsCOMPtr<nsIPrincipal> principal =
+        BasePrincipal::CreateContentPrincipal(uri, GetOriginAttributes());
+    if (!principal) {
+      NS_WARNING("Invalid RemoteType: Failed to create content principal");
+      return false;
+    }
+
+    // Currently we always isolate by site, never by origin, so a remote type
+    // should only contain a site origin.
+    nsAutoCString origin;
+    nsAutoCString siteOrigin;
+    MOZ_ALWAYS_SUCCEEDS(principal->GetOriginNoSuffix(origin));
+    MOZ_ALWAYS_SUCCEEDS(principal->GetSiteOriginNoSuffix(siteOrigin));
+    if (origin != mOriginNoSuffix || origin != siteOrigin) {
+      NS_WARNING("Invalid RemoteType: Non-canonical OriginNoSuffix");
+      return false;
+    }
+  } else if (IsWebCoopCoep() || IsWebServiceWorker()) {
+    // These remote types require a URI specified.
+    NS_WARNING(
+        "Invalid RemoteType: Web{CoopCoep/ServiceWorker} without site origin");
+    return false;
+  }
+
+  return true;
+}
+
+bool RemoteType::SupportsPrealloc() const {
+  MOZ_ASSERT(IsKnown());
+  MOZ_ASSERT(mKind != Kind::Prealloc);
+
+  // NOTE: Extension processes do not support prealloc due to bug 1638119
+  return mKind != Kind::NotRemote && mKind != Kind::File &&
+         mKind != Kind::PrivilegedAbout && mKind != Kind::Extension &&
+         !mDisableJit;
+}
+
+OriginAttributes RemoteType::GetOriginAttributes() const {
+  OriginAttributes attrs;
+  attrs.mUserContextId = mUserContextId;
+  attrs.mPrivateBrowsingId = mPrivateBrowsingId;
+  attrs.mGeckoViewSessionContextId = mGeckoViewSessionContextId;
+  return attrs;
+}
+
+RemoteType RemoteType::WithDisableJit(bool aDisableJit) const {
+  MOZ_RELEASE_ASSERT(IsWeb());
+  RemoteType copy(*this);
+  copy.mDisableJit = aDisableJit;
+
+  MOZ_ASSERT(copy.CheckValidity());
+  return copy;
+}
+
+RemoteType RemoteType::WithSiteOrigin(const nsACString& aSiteOriginNoSuffix,
+                                      Kind aNewKind) const {
+  MOZ_RELEASE_ASSERT(IsSharedWeb());
+  RemoteType copy(*this);
+  copy.mKind = aNewKind;
+  copy.mOriginNoSuffix = aSiteOriginNoSuffix;
+
+  // NOTE: We release-assert validity, as an invalid aSiteOriginURI or Kind
+  // could create an invalid RemoteType.
+  MOZ_RELEASE_ASSERT(copy.CheckValidity());
+  MOZ_RELEASE_ASSERT(copy.IsIsolatedWeb());
+  return copy;
+}
+
+}  // namespace mozilla::dom
+
+// NOTE: This could probably be made more efficient by removing the
+// serialization to a string, but this keeps the logic simpler for now.
+namespace IPC {
+
+void ParamTraits<mozilla::dom::RemoteType>::Write(MessageWriter* aWriter,
+                                                  const paramType& aParam) {
+  MOZ_ASSERT(aParam.IsKnown(), "Cannot send unknown RemoteType");
+  WriteParam(aWriter, aParam.Stringify());
+}
+
+bool ParamTraits<mozilla::dom::RemoteType>::Read(MessageReader* aReader,
+                                                 paramType* aResult) {
+  nsCString s;
+  if (!ReadParam(aReader, &s)) {
+    return false;
+  }
+  *aResult = mozilla::dom::RemoteType::Parse(s);
+  return aResult->IsKnown();
+}
+
+}  // namespace IPC
diff --git a/dom/ipc/RemoteType.h b/dom/ipc/RemoteType.h
index 673135d1f518..08ea9dae3440 100644
--- a/dom/ipc/RemoteType.h
+++ b/dom/ipc/RemoteType.h
@@ -5,33 +5,251 @@
 #ifndef mozilla_dom_RemoteType_h
 #define mozilla_dom_RemoteType_h
 
-#include "nsReadableUtils.h"
+#include "mozilla/HashFunctions.h"
 #include "nsString.h"
 
-// These must match the similar ones in E10SUtils.sys.mjs and ProcInfo.h and
-// ChromeUtils.webidl Process names as reported by about:memory are defined in
-// ContentChild:RecvRemoteType.  Add your value there too or it will be called
-// "Web Content".
-#define PREALLOC_REMOTE_TYPE "prealloc"_ns
-#define WEB_REMOTE_TYPE "web"_ns
-#define FILE_REMOTE_TYPE "file"_ns
-#define EXTENSION_REMOTE_TYPE "extension"_ns
-#define PRIVILEGEDABOUT_REMOTE_TYPE "privilegedabout"_ns
-#define PRIVILEGEDMOZILLA_REMOTE_TYPE "privilegedmozilla"_ns
-#define INFERENCE_REMOTE_TYPE "inference"_ns
+namespace mozilla {
+class OriginAttributes;
+}
 
-#define DEFAULT_REMOTE_TYPE WEB_REMOTE_TYPE
+namespace IPC {
+template <typename T>
+struct ParamTraits;
+class MessageWriter;
+class MessageReader;
+}  // namespace IPC
 
-// These must start with the WEB_REMOTE_TYPE above.
-#define FISSION_WEB_REMOTE_TYPE "webIsolated"_ns
-#define WITH_COOP_COEP_REMOTE_TYPE "webCOOP+COEP"_ns
-#define WITH_COOP_COEP_REMOTE_TYPE_PREFIX "webCOOP+COEP="_ns
-#define SERVICEWORKER_REMOTE_TYPE "webServiceWorker"_ns
+namespace mozilla::dom {
 
-// A flag appended to the origin suffix to disable the JIT for that process.
-#define DISABLE_JIT_REMOTE_TYPE_SUFFIX "disableJit=1"_ns
+/**
+ * Parsed information about a given RemoteType string. A remote type is used as
+ * the key for determining which process type to load in.
+ */
+struct RemoteType {
+  // Primary "Kind" enum for the remote type.
+  //
+  // These must match the similar ones in E10SUtils.sys.mjs and ProcInfo.h and
+  // ChromeUtils.webidl.  Process names as reported by about:memory are defined
+  // in ContentChild:RecvSetRemoteType.  Add your value there too or it will be
+  // called "Web Content".
+  enum class Kind : uint8_t {
+    // Error case for an "invalid" RemoteType instance.
+    // Remote Types of this Kind are falsy, and cannot be sent over IPC.
+    Unknown,
 
-// Remote type value used to represent being non-remote.
-#define NOT_REMOTE_TYPE VoidCString()
+    // The parent process.
+    // This process is exclusively used for displaying core and/or legacy
+    // trusted browser UI.
+    NotRemote,
+
+    // An unspecialized content process, which has loaded nothing.
+    // Only a process with this Kind can change its RemoteType at runtime.
+    Prealloc,
+
+    // Process used to host arbitrary untrusted web content.
+    // Privileged interfaces should not be exposed to web content processes.
+    WebContent,
+
+    // Process used to host arbitrary untrusted web content with the COOP and
+    // COEP headers.
+    // Privileged interfaces should not be exposed to web content processes.
+    WebCoopCoep,
+
+    // Process used to host arbitrary untrusted web service workers.
+    // Privileged interfaces should not be exposed to web content processes.
+    WebServiceWorker,
+
+    // Process used to host arbitrary untrusted content from the local
+    // filesystem (i.e. file:/// URIs).
+    // This process is less sandboxed, as by necessity it is allowed to read the
+    // local filesystem.
+    File,
+
+    // Process used to host privileged browser UI.
+    // Privileged APIs used by pages like the newtab page must be restricted to
+    // only be usable within this remote type.
+    PrivilegedAbout,
+
+    // Process used to host privileged web content, such as AMO and SUMO.
+    PrivilegedMozilla,
+
+    // Process used to host WebExtension content, including background scripts,
+    // toplevel documents, and service workers.
+    Extension,
+
+    // Process used to host inference models.
+    Inference,
+  };
+
+  // Static getter for the NotRemote remote type.
+  //
+  // This returns a `const RemoteType&` referencing a static `NotRemote` type to
+  // allow returning this type in context which otherwise would return a `const
+  // RemoteType&`.
+  //
+  // Other kinds should use the normal `RemoteType` constructor or `SharedWeb`
+  static const RemoteType& NotRemote();
+
+  // Static factory method for Web remote types.
+  //
+  // This creates a SharedWeb remote type without site isolation or other
+  // customizations. Use the `With*` methods to create isolated remote types.
+  static RemoteType SharedWeb(const OriginAttributes& aAttrs);
+
+  RemoteType();
+  ~RemoteType();
+  RemoteType(const RemoteType&);
+  RemoteType& operator=(const RemoteType&);
+
+  // NOTE: Currently we don't support move operators.
+  // If we decide to implement them in the future, it should probably be done
+  // manually to ensure the moved-from RemoteType becomes Unknown.
+
+  explicit RemoteType(Kind aKind);
+
+  // Support for equality & hashing operations on the RemoteType object.
+  bool operator==(const RemoteType& aOther) const;
+  bool operator!=(const RemoteType& aOther) const { return !(*this == aOther); }
+  HashNumber Hash() const;
+
+  // Checking for validity.
+  bool IsKnown() const { return mKind != Kind::Unknown; }
+  explicit operator bool() const { return IsKnown(); }
+
+  // Attempts to parse a stringified RemoteType.
+  // On failure, returns an `Unknown` RemoteType object.
+  static RemoteType Parse(const nsACString& aRemoteType);
+
+  // Convert a parsed RemoteType back into its string representation.
+  // WARNING: The resulting value is not Telemetry-safe, see StringifyKind().
+  nsCString Stringify() const;
+
+  // Get a telemetry-safe kind string for this RemoteType.
+  nsCString StringifyKind() const;
+
+  // String value encoding RemoteType metadata (e.g. site origin & OAs).
+  // WARNING: The resulting value is not Telemetry-safe.
+  nsAutoCString StringifyMeta() const;
+
+  // Which kind of RemoteType is this? You can also use the helper methods below
+  // instead of matching on every case.
+  Kind GetKind() const { return mKind; }
+
+  // Get the [Site]OriginNoSuffix used for isolating this process.
+  // Only valid to call if HasOrigin().
+  const nsCString& OriginNoSuffix() const {
+    MOZ_ASSERT(HasOrigin());
+    return mOriginNoSuffix;
+  }
+
+  // NOTE: These origin attributes are only specified for web remote types, and
+  // will be left as default for all other remote types.
+  uint32_t UserContextId() const { return mUserContextId; }
+  uint32_t PrivateBrowsingId() const { return mPrivateBrowsingId; }
+  bool IsPrivateBrowsing() const { return mPrivateBrowsingId != 0; }
+  const nsString& GeckoViewSessionContextId() const {
+    return mGeckoViewSessionContextId;
+  }
+
+  OriginAttributes GetOriginAttributes() const;
+
+  // Check if there are any non-default attributes.
+  bool HasAttrs() const;
+  bool HasOrigin() const { return !mOriginNoSuffix.IsEmpty(); }
+  bool HasMeta() const { return HasOrigin() || HasAttrs(); }
+
+  bool IsNotRemote() const { return mKind == Kind::NotRemote; }
+  bool IsPrealloc() const { return mKind == Kind::Prealloc; }
+  bool IsWeb() const {
+    return mKind == Kind::WebContent || mKind == Kind::WebCoopCoep ||
+           mKind == Kind::WebServiceWorker;
+  }
+  bool IsSharedWeb() const { return IsWeb() && !HasOrigin(); }
+  bool IsIsolatedWeb() const { return IsWeb() && HasOrigin(); }
+  bool IsWebCoopCoep() const { return mKind == Kind::WebCoopCoep; }
+  bool IsWebServiceWorker() const { return mKind == Kind::WebServiceWorker; }
+  bool IsFile() const { return mKind == Kind::File; }
+  bool IsPrivilegedAbout() const { return mKind == Kind::PrivilegedAbout; }
+  bool IsPrivilegedMozilla() const { return mKind == Kind::PrivilegedMozilla; }
+  bool IsExtension() const { return mKind == Kind::Extension; }
+  bool IsInference() const { return mKind == Kind::Inference; }
+  bool IsJitDisabled() const { return mDisableJit; }
+
+  // Does this RemoteType support being created from a prealloc process?
+  bool SupportsPrealloc() const;
+
+  // Construct a new RemoteType identical to the current RemoteType, but with
+  // the "disableJit" flag set.
+  // WARNING: Asserts if called on a non-Web remote type.
+  RemoteType WithDisableJit(bool aDisableJit) const;
+
+  // Turn this shared web RemoteType into an IsolatedWeb RemoteType which is
+  // isolated by the provided SiteOriginNoSuffix. A specific kind for the
+  // isolated remoteType can also be provided, and must be WebContent,
+  // WebServiceWorker, or WebCoopCoep.
+  // WARNING: Asserts if called on a non-SharedWeb remote type.
+  RemoteType WithSiteOrigin(const nsACString& aSiteOriginNoSuffix,
+                            Kind aNewKind = Kind::WebContent) const;
+
+  // Allow formatting a RemoteType with {fmt} or operator<<
+  friend nsCString format_as(const RemoteType& aRemoteType) {
+    return aRemoteType.Stringify();
+  }
+  friend std::ostream& operator<<(std::ostream& aStream,
+                                  const RemoteType& aRemoteType) {
+    return aStream << aRemoteType.Stringify();
+  }
+
+ private:
+  // Implementation detail of `Parse`, which does not assert validity.
+  static RemoteType ParseNoValidityCheck(const nsACString& aRemoteType);
+
+  // Check that the given RemoteType does not violate any internal invariants.
+  // An invalid RemoteType should never be exposed outside of RemoteType
+  // internals, so this is private.
+  [[nodiscard]] bool CheckValidity() const;
+
+  Kind mKind = Kind::Unknown;
+
+  // Additional Isolation Flags.
+  bool mDisableJit = false;
+
+  // The [Site]OriginNoSuffix used for isolating this process.
+  nsCString mOriginNoSuffix;
+
+  // This is a subset of the members from `OriginAttributes`, which are allowed
+  // to influence process selection.
+  uint32_t mUserContextId = 0;
+  uint32_t mPrivateBrowsingId = 0;
+  nsString mGeckoViewSessionContextId;
+
+  template <typename T>
+  struct Attr {
+    nsLiteralCString mName;
+    T RemoteType::* mMember;
+  };
+
+  // Tuple describing the various RemoteType attributes which should be
+  // serialized into the remote type with URIParams.
+  static constexpr std::tuple kAttrs{
+      Attr{"userContextId"_ns, &RemoteType::mUserContextId},
+      Attr{"privateBrowsingId"_ns, &RemoteType::mPrivateBrowsingId},
+      Attr{"geckoViewUserContextId"_ns,
+           &RemoteType::mGeckoViewSessionContextId},
+      Attr{"disableJit"_ns, &RemoteType::mDisableJit}};
+};
+
+}  // namespace mozilla::dom
+
+namespace IPC {
+
+template <>
+struct ParamTraits<mozilla::dom::RemoteType> {
+  using paramType = mozilla::dom::RemoteType;
+  static void Write(MessageWriter* aWriter, const paramType& aParam);
+  static bool Read(MessageReader* aReader, paramType* aResult);
+};
+
+}  // namespace IPC
 
 #endif  // mozilla_dom_RemoteType_h
diff --git a/dom/ipc/WindowGlobalChild.cpp b/dom/ipc/WindowGlobalChild.cpp
index 9364d783a1f7..79524b0f44b4 100644
--- a/dom/ipc/WindowGlobalChild.cpp
+++ b/dom/ipc/WindowGlobalChild.cpp
@@ -712,7 +712,7 @@ mozilla::ipc::IPCResult WindowGlobalChild::RecvMakeFrameLocal(
 
   // Trigger a process switch into the current process.
   RemotenessOptions options;
-  options.mRemoteType = NOT_REMOTE_TYPE;
+  options.mRemoteType = dom::RemoteType::NotRemote().Stringify();
   options.mPendingSwitchID.Construct(aPendingSwitchId);
   options.mSwitchingInProgressLoad = true;
   flo->ChangeRemoteness(options, IgnoreErrors());
@@ -1083,12 +1083,12 @@ void WindowGlobalChild::SetDocumentURI(nsIURI* aDocumentURI) {
   SendUpdateDocumentURI(WrapNotNull(aDocumentURI));
 }
 
-const nsACString& WindowGlobalChild::GetRemoteType() const {
+const RemoteType& WindowGlobalChild::GetRemoteType() const {
   if (XRE_IsContentProcess()) {
     return ContentChild::GetSingleton()->GetRemoteType();
   }
 
-  return NOT_REMOTE_TYPE;
+  return RemoteType::NotRemote();
 }
 
 already_AddRefed<JSWindowActorChild> WindowGlobalChild::GetActor(
diff --git a/dom/ipc/WindowGlobalChild.h b/dom/ipc/WindowGlobalChild.h
index 3678769f47a4..b20139f56132 100644
--- a/dom/ipc/WindowGlobalChild.h
+++ b/dom/ipc/WindowGlobalChild.h
@@ -155,7 +155,7 @@ class WindowGlobalChild final : public WindowGlobalActor,
   void BlockBFCacheFor(BFCacheStatus aStatus);
 
  protected:
-  const nsACString& GetRemoteType() const override;
+  const RemoteType& GetRemoteType() const override;
 
   already_AddRefed<JSActor> InitJSActor(JS::Handle<JSObject*> aMaybeActor,
                                         const nsACString& aName,
diff --git a/dom/ipc/WindowGlobalParent.cpp b/dom/ipc/WindowGlobalParent.cpp
index a0c27a446c6b..e2337fa9db52 100644
--- a/dom/ipc/WindowGlobalParent.cpp
+++ b/dom/ipc/WindowGlobalParent.cpp
@@ -676,16 +676,16 @@ IPCResult WindowGlobalParent::RecvRawMessage(const JSActorMessageMeta& aMeta,
   return IPC_OK();
 }
 
-const nsACString& WindowGlobalParent::GetRemoteType() const {
+const RemoteType& WindowGlobalParent::GetRemoteType() const {
   if (RefPtr<BrowserParent> browserParent = GetBrowserParent()) {
     return browserParent->Manager()->GetRemoteType();
   }
 
-  return NOT_REMOTE_TYPE;
+  return RemoteType::NotRemote();
 }
 
 void WindowGlobalParent::GetRemoteType(nsACString& aRemoteType) const {
-  aRemoteType = GetRemoteType();
+  aRemoteType = GetRemoteType().Stringify();
 }
 
 void WindowGlobalParent::NotifyContentBlockingEvent(
@@ -2065,8 +2065,7 @@ bool WindowGlobalParent::ShouldTrackSiteOriginTelemetry() {
   }
 
   RefPtr<BrowserParent> browserParent = GetBrowserParent();
-  if (!browserParent ||
-      !IsWebRemoteType(browserParent->Manager()->GetRemoteType())) {
+  if (!browserParent || !browserParent->Manager()->GetRemoteType().IsWeb()) {
     return false;
   }
 
diff --git a/dom/ipc/WindowGlobalParent.h b/dom/ipc/WindowGlobalParent.h
index 7b7818b29e15..55c881a76dc8 100644
--- a/dom/ipc/WindowGlobalParent.h
+++ b/dom/ipc/WindowGlobalParent.h
@@ -270,7 +270,7 @@ class WindowGlobalParent final : public WindowContext,
   void AddSecurityState(uint32_t aStateFlags);
   uint32_t GetSecurityFlags() { return mSecurityState; }
 
-  const nsACString& GetRemoteType() const override;
+  const RemoteType& GetRemoteType() const override;
   void GetRemoteType(nsACString& aRemoteType) const;
 
   void NotifySessionStoreUpdatesComplete(Element* aEmbedder);
diff --git a/dom/ipc/gtest/ProcessIsolationTest.cpp b/dom/ipc/gtest/ProcessIsolationTest.cpp
index b448148ccc51..cd466dd62aff 100644
--- a/dom/ipc/gtest/ProcessIsolationTest.cpp
+++ b/dom/ipc/gtest/ProcessIsolationTest.cpp
@@ -31,8 +31,8 @@ namespace {
 static bool gJitDisabled = false;
 
 struct RemoteTypes {
-  nsCString mIsolated;
-  nsCString mUnisolated;
+  RemoteType mIsolated;
+  RemoteType mUnisolated;
 };
 
 struct WorkerExpectation {
@@ -40,7 +40,7 @@ struct WorkerExpectation {
   WorkerKind mWorkerKind = WorkerKindShared;
   bool mJitDisabled = false;
   Result<RemoteTypes, nsresult> mExpected = Err(NS_ERROR_FAILURE);
-  nsCString mCurrentRemoteType = "fakeRemoteType"_ns;
+  RemoteType mCurrentRemoteType = RemoteType(RemoteType::Kind::WebContent);
 
   void Check(bool aUseRemoteSubframes) {
     nsAutoCString origin;
@@ -50,7 +50,7 @@ struct WorkerExpectation {
         "origin: %s, workerKind: %s, currentRemoteType: %s, "
         "useRemoteSubframes: %d",
         origin.get(), mWorkerKind == WorkerKindShared ? "shared" : "service",
-        mCurrentRemoteType.get(), aUseRemoteSubframes);
+        mCurrentRemoteType.Stringify().get(), aUseRemoteSubframes);
 
     gJitDisabled = mJitDisabled;
     auto result = IsolationOptionsForWorker(
@@ -59,12 +59,14 @@ struct WorkerExpectation {
         << "Unexpected status (expected " << (mExpected.isOk() ? "ok" : "err")
         << ") for " << describe;
     if (mExpected.isOk()) {
-      const nsCString& expected = aUseRemoteSubframes
-                                      ? mExpected.inspect().mIsolated
-                                      : mExpected.inspect().mUnisolated;
+      const RemoteType& expected = aUseRemoteSubframes
+                                       ? mExpected.inspect().mIsolated
+                                       : mExpected.inspect().mUnisolated;
+      EXPECT_TRUE(expected.IsKnown())
+          << "invalid remote type expectation in test";
       ASSERT_EQ(result.inspect().mRemoteType, expected)
-          << "Unexpected remote type (expected " << expected << ") for "
-          << describe;
+          << "Unexpected remote type (expected " << expected.Stringify()
+          << ") for " << describe;
     }
   }
 };
@@ -153,37 +155,11 @@ static void UnregisterMockPolicyService() {
 
 }  // namespace
 
-static nsCString WebIsolatedRemoteType(nsIPrincipal* aPrincipal,
-                                       bool aJitDisabled = false) {
-  nsAutoCString origin;
-  MOZ_ALWAYS_SUCCEEDS(aPrincipal->GetSiteOrigin(origin));
-  if (aJitDisabled) {
-    return FISSION_WEB_REMOTE_TYPE + "="_ns + origin + "^disableJit=1"_ns;
-  }
-  return FISSION_WEB_REMOTE_TYPE + "="_ns + origin;
-}
-
-static nsCString CoopCoepRemoteType(nsIPrincipal* aPrincipal) {
-  nsAutoCString origin;
-  MOZ_ALWAYS_SUCCEEDS(aPrincipal->GetSiteOrigin(origin));
-  return WITH_COOP_COEP_REMOTE_TYPE + "="_ns + origin;
-}
-
-static nsCString ServiceWorkerIsolatedRemoteType(nsIPrincipal* aPrincipal,
-                                                 bool aJitDisabled = false) {
-  nsAutoCString origin;
-  MOZ_ALWAYS_SUCCEEDS(aPrincipal->GetSiteOrigin(origin));
-  if (aJitDisabled) {
-    return SERVICEWORKER_REMOTE_TYPE + "="_ns + origin + "^disableJit=1"_ns;
-  }
-  return SERVICEWORKER_REMOTE_TYPE + "="_ns + origin;
-}
-
 // When file URI process separation is disabled (as is the default on
 // Android), a file: shared worker is allowed to load in any remote type,
 // rather than being rejected when it isn't already in a file: process.
 static Result<RemoteTypes, nsresult> FileWorkerOutsideFileProcessExpected(
-    const nsCString& aFileRemoteType) {
+    const RemoteType& aFileRemoteType) {
   if (StaticPrefs::browser_tabs_remote_separateFileUriProcess()) {
     return Err(NS_ERROR_UNEXPECTED);
   }
@@ -230,14 +206,14 @@ TEST(ProcessIsolationTest, WorkerOptions)
   nsCOMPtr<nsIPrincipal> nullSecureComPrecursorPrincipal =
       NullPrincipal::CreateWithInheritedAttributes(secureComPrincipal);
 
-  nsCString extensionRemoteType =
+  RemoteType extensionRemoteType =
       ExtensionPolicyService::GetSingleton().UseRemoteExtensions()
-          ? EXTENSION_REMOTE_TYPE
-          : NOT_REMOTE_TYPE;
-  nsCString fileRemoteType =
+          ? RemoteType(RemoteType::Kind::Extension)
+          : RemoteType::NotRemote();
+  RemoteType fileRemoteType =
       StaticPrefs::browser_tabs_remote_separateFileUriProcess()
-          ? FILE_REMOTE_TYPE
-          : WEB_REMOTE_TYPE;
+          ? RemoteType(RemoteType::Kind::File)
+          : RemoteType(RemoteType::Kind::WebContent);
 
   WorkerExpectation expectations[] = {
       // Neither service not shared workers can have expanded principals
@@ -265,55 +241,62 @@ TEST(ProcessIsolationTest, WorkerOptions)
       // Service workers with various content principals
       {.mPrincipal = secureComPrincipal,
        .mWorkerKind = WorkerKindService,
-       .mExpected =
-           RemoteTypes{ServiceWorkerIsolatedRemoteType(secureComPrincipal),
-                       WEB_REMOTE_TYPE}},
+       .mExpected = RemoteTypes{RemoteType::Parse(
+                                    "webServiceWorker=https://example.com"_ns),
+                                RemoteType(RemoteType::Kind::WebContent)}},
       {.mPrincipal = secureOrgPrincipal,
        .mWorkerKind = WorkerKindService,
-       .mExpected =
-           RemoteTypes{ServiceWorkerIsolatedRemoteType(secureOrgPrincipal),
-                       WEB_REMOTE_TYPE}},
+       .mExpected = RemoteTypes{RemoteType::Parse(
+                                    "webServiceWorker=https://example.org"_ns),
+                                RemoteType(RemoteType::Kind::WebContent)}},
       {.mPrincipal = extensionPrincipal,
        .mWorkerKind = WorkerKindService,
        .mExpected = RemoteTypes{extensionRemoteType, extensionRemoteType},
-       .mCurrentRemoteType = EXTENSION_REMOTE_TYPE},
+       .mCurrentRemoteType = RemoteType(RemoteType::Kind::Extension)},
       {.mPrincipal = privilegedMozillaPrincipal,
        .mWorkerKind = WorkerKindService,
        .mExpected = Err(NS_ERROR_UNEXPECTED)},
       {.mPrincipal = privilegedMozillaPrincipal,
        .mWorkerKind = WorkerKindService,
-       .mExpected = RemoteTypes{PRIVILEGEDMOZILLA_REMOTE_TYPE,
-                                PRIVILEGEDMOZILLA_REMOTE_TYPE},
-       .mCurrentRemoteType = PRIVILEGEDMOZILLA_REMOTE_TYPE},
+       .mExpected =
+           RemoteTypes{RemoteType(RemoteType::Kind::PrivilegedMozilla),
+                       RemoteType(RemoteType::Kind::PrivilegedMozilla)},
+       .mCurrentRemoteType = RemoteType(RemoteType::Kind::PrivilegedMozilla)},
 
       // Shared Worker loaded from within a webCOOP+COEP remote type process,
       // should load elsewhere.
       {.mPrincipal = secureComPrincipal,
        .mWorkerKind = WorkerKindShared,
-       .mExpected = RemoteTypes{WebIsolatedRemoteType(secureComPrincipal),
-                                WEB_REMOTE_TYPE},
-       .mCurrentRemoteType = CoopCoepRemoteType(secureComPrincipal)},
+       .mExpected =
+           RemoteTypes{RemoteType::Parse("webIsolated=https://example.com"_ns),
+                       RemoteType(RemoteType::Kind::WebContent)},
+       .mCurrentRemoteType =
+           RemoteType::Parse("webCOOP+COEP=https://example.com"_ns)},
 
       // Even precursorless null principal should load elsewhere.
       {.mPrincipal = nullPrincipal,
        .mWorkerKind = WorkerKindShared,
-       .mExpected = RemoteTypes{WEB_REMOTE_TYPE, WEB_REMOTE_TYPE},
-       .mCurrentRemoteType = CoopCoepRemoteType(secureComPrincipal)},
+       .mExpected = RemoteTypes{RemoteType(RemoteType::Kind::WebContent),
+                                RemoteType(RemoteType::Kind::WebContent)},
+       .mCurrentRemoteType =
+           RemoteType::Parse("webCOOP+COEP=https://example.com"_ns)},
       {.mPrincipal = nullContainerPrincipal,
        .mWorkerKind = WorkerKindShared,
-       .mExpected = RemoteTypes{WEB_REMOTE_TYPE "=^userContextId=1"_ns,
-                                WEB_REMOTE_TYPE "=^userContextId=1"_ns},
-       .mCurrentRemoteType = CoopCoepRemoteType(secureComPrincipal)},
+       .mExpected = RemoteTypes{RemoteType::Parse("web=^userContextId=1"_ns),
+                                RemoteType::Parse("web=^userContextId=1"_ns)},
+       .mCurrentRemoteType =
+           RemoteType::Parse("webCOOP+COEP=https://example.com"_ns)},
 
       // System principal shared workers can only load in the parent process.
       {.mPrincipal = systemPrincipal,
        .mWorkerKind = WorkerKindShared,
-       .mExpected = RemoteTypes{NOT_REMOTE_TYPE, NOT_REMOTE_TYPE},
-       .mCurrentRemoteType = NOT_REMOTE_TYPE},
+       .mExpected =
+           RemoteTypes{RemoteType::NotRemote(), RemoteType::NotRemote()},
+       .mCurrentRemoteType = RemoteType::NotRemote()},
       {.mPrincipal = systemPrincipal,
        .mWorkerKind = WorkerKindShared,
        .mExpected = Err(NS_ERROR_UNEXPECTED),
-       .mCurrentRemoteType = PRIVILEGEDABOUT_REMOTE_TYPE},
+       .mCurrentRemoteType = RemoteType(RemoteType::Kind::PrivilegedAbout)},
       {.mPrincipal = systemPrincipal,
        .mWorkerKind = WorkerKindShared,
        .mExpected = Err(NS_ERROR_UNEXPECTED)},
@@ -324,53 +307,62 @@ TEST(ProcessIsolationTest, WorkerOptions)
       // Content principals should load in the appropriate remote types.
       {.mPrincipal = secureComPrincipal,
        .mWorkerKind = WorkerKindShared,
-       .mExpected = RemoteTypes{WebIsolatedRemoteType(secureComPrincipal),
-                                WEB_REMOTE_TYPE}},
+       .mExpected =
+           RemoteTypes{RemoteType::Parse("webIsolated=https://example.com"_ns),
+                       RemoteType(RemoteType::Kind::WebContent)}},
       {.mPrincipal = secureOrgPrincipal,
        .mWorkerKind = WorkerKindShared,
-       .mExpected = RemoteTypes{WebIsolatedRemoteType(secureOrgPrincipal),
-                                WEB_REMOTE_TYPE}},
+       .mExpected =
+           RemoteTypes{RemoteType::Parse("webIsolated=https://example.org"_ns),
+                       RemoteType(RemoteType::Kind::WebContent)}},
       {.mPrincipal = insecureOrgPrincipal,
        .mWorkerKind = WorkerKindShared,
-       .mExpected = RemoteTypes{WebIsolatedRemoteType(insecureOrgPrincipal),
-                                WEB_REMOTE_TYPE}},
+       .mExpected =
+           RemoteTypes{RemoteType::Parse("webIsolated=http://example.org"_ns),
+                       RemoteType(RemoteType::Kind::WebContent)}},
       {.mPrincipal = filePrincipal,
        .mWorkerKind = WorkerKindShared,
        .mExpected = FileWorkerOutsideFileProcessExpected(fileRemoteType)},
       {.mPrincipal = filePrincipal,
        .mWorkerKind = WorkerKindShared,
        .mExpected = RemoteTypes{fileRemoteType, fileRemoteType},
-       .mCurrentRemoteType = FILE_REMOTE_TYPE},
+       .mCurrentRemoteType = RemoteType(RemoteType::Kind::File)},
       {.mPrincipal = extensionPrincipal,
        .mWorkerKind = WorkerKindShared,
        .mExpected = RemoteTypes{extensionRemoteType, extensionRemoteType},
-       .mCurrentRemoteType = EXTENSION_REMOTE_TYPE},
+       .mCurrentRemoteType = RemoteType(RemoteType::Kind::Extension)},
       {.mPrincipal = privilegedMozillaPrincipal,
        .mWorkerKind = WorkerKindShared,
        .mExpected = Err(NS_ERROR_UNEXPECTED)},
       {.mPrincipal = privilegedMozillaPrincipal,
        .mWorkerKind = WorkerKindShared,
-       .mExpected = RemoteTypes{PRIVILEGEDMOZILLA_REMOTE_TYPE,
-                                PRIVILEGEDMOZILLA_REMOTE_TYPE},
-       .mCurrentRemoteType = PRIVILEGEDMOZILLA_REMOTE_TYPE},
+       .mExpected =
+           RemoteTypes{RemoteType(RemoteType::Kind::PrivilegedMozilla),
+                       RemoteType(RemoteType::Kind::PrivilegedMozilla)},
+       .mCurrentRemoteType = RemoteType(RemoteType::Kind::PrivilegedMozilla)},
       {.mPrincipal = nullSecureComPrecursorPrincipal,
        .mWorkerKind = WorkerKindShared,
-       .mExpected = RemoteTypes{WebIsolatedRemoteType(secureComPrincipal),
-                                WEB_REMOTE_TYPE}},
+       .mExpected =
+           RemoteTypes{RemoteType::Parse("webIsolated=https://example.com"_ns),
+                       RemoteType(RemoteType::Kind::WebContent)}},
 
       // When the policy service calls for the JIT to be disabled the remote
       // type should reflect that.
       {.mPrincipal = secureComPrincipal,
        .mWorkerKind = WorkerKindShared,
        .mJitDisabled = true,
-       .mExpected = RemoteTypes{WebIsolatedRemoteType(secureComPrincipal, true),
-                                SharedWebRemoteType(OriginAttributes{}, true)}},
+       .mExpected =
+           RemoteTypes{RemoteType::Parse(
+                           "webIsolated=https://example.com^disableJit=1"_ns),
+                       RemoteType::Parse("web=^disableJit=1"_ns)}},
       {.mPrincipal = secureComPrincipal,
        .mWorkerKind = WorkerKindService,
        .mJitDisabled = true,
-       .mExpected = RemoteTypes{ServiceWorkerIsolatedRemoteType(
-                                    secureComPrincipal, true),
-                                SharedWebRemoteType(OriginAttributes{}, true)}},
+       .mExpected =
+           RemoteTypes{
+               RemoteType::Parse(
+                   "webServiceWorker=https://example.com^disableJit=1"_ns),
+               RemoteType::Parse("web=^disableJit=1"_ns)}},
   };
 
   RegisterMockPolicyService();
@@ -413,10 +405,10 @@ TEST(ProcessIsolationTest, FileURIAllowlistedWorkerOptions)
   nsCOMPtr<nsIPrincipal> filePrincipal =
       MakeTestPrincipal("file:///path/to/dir");
 
-  nsCString fileRemoteType =
+  RemoteType fileRemoteType(
       StaticPrefs::browser_tabs_remote_separateFileUriProcess()
-          ? FILE_REMOTE_TYPE
-          : WEB_REMOTE_TYPE;
+          ? RemoteType::Kind::File
+          : RemoteType::Kind::WebContent);
 
   WorkerExpectation expectations[] = {
       // Being in the file:// URI allowlist must not change worker process
@@ -425,15 +417,16 @@ TEST(ProcessIsolationTest, FileURIAllowlistedWorkerOptions)
       // ServiceWorkerPrivate::Initialize() passes for a service worker.
       {.mPrincipal = allowlistedPrincipal,
        .mWorkerKind = WorkerKindService,
-       .mExpected =
-           RemoteTypes{ServiceWorkerIsolatedRemoteType(allowlistedPrincipal),
-                       WEB_REMOTE_TYPE},
-       .mCurrentRemoteType = WEB_REMOTE_TYPE},
+       .mExpected = RemoteTypes{RemoteType::Parse(
+                                    "webServiceWorker=https://example.com"_ns),
+                                RemoteType(RemoteType::Kind::WebContent)},
+       .mCurrentRemoteType = RemoteType(RemoteType::Kind::WebContent)},
       {.mPrincipal = allowlistedPrincipal,
        .mWorkerKind = WorkerKindShared,
-       .mExpected = RemoteTypes{WebIsolatedRemoteType(allowlistedPrincipal),
-                                WEB_REMOTE_TYPE},
-       .mCurrentRemoteType = WEB_REMOTE_TYPE},
+       .mExpected =
+           RemoteTypes{RemoteType::Parse("webIsolated=https://example.com"_ns),
+                       RemoteType(RemoteType::Kind::WebContent)},
+       .mCurrentRemoteType = RemoteType(RemoteType::Kind::WebContent)},
 
       // An actual file: principal is still confined to the file process,
       // regardless of the allowlist.
@@ -443,7 +436,7 @@ TEST(ProcessIsolationTest, FileURIAllowlistedWorkerOptions)
       {.mPrincipal = filePrincipal,
        .mWorkerKind = WorkerKindShared,
        .mExpected = RemoteTypes{fileRemoteType, fileRemoteType},
-       .mCurrentRemoteType = FILE_REMOTE_TYPE},
+       .mCurrentRemoteType = RemoteType(RemoteType::Kind::File)},
   };
 
   for (auto& expectation : expectations) {
diff --git a/dom/ipc/gtest/RemoteTypeTest.cpp b/dom/ipc/gtest/RemoteTypeTest.cpp
new file mode 100644
index 000000000000..af4e8ad18f82
--- /dev/null
+++ b/dom/ipc/gtest/RemoteTypeTest.cpp
@@ -0,0 +1,153 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "gtest/gtest.h"
+#include "mozilla/OriginAttributes.h"
+#include "mozilla/dom/RemoteType.h"
+#include "mozilla/gtest/MozAssertions.h"
+
+namespace mozilla::dom {
+
+TEST(RemoteTypeTest, FormatSimple)
+{
+  // NotRemote is special in that it has a different value for Stringify() and
+  // StringifyKind(). This will be changed in the future.
+  EXPECT_TRUE(RemoteType::NotRemote().IsKnown());
+  EXPECT_EQ(RemoteType::NotRemote().Stringify(), VoidCString());
+  EXPECT_EQ(RemoteType::NotRemote().StringifyKind(), "parent"_ns);
+  EXPECT_FALSE(RemoteType::NotRemote().HasMeta());
+  EXPECT_EQ(RemoteType::NotRemote().StringifyMeta(), ""_ns);
+
+  auto formatSimple = [](RemoteType::Kind aKind, const nsACString& aString) {
+    RemoteType remoteType(aKind);
+    EXPECT_TRUE(remoteType.IsKnown());
+    EXPECT_EQ(remoteType.StringifyKind(), aString);
+    EXPECT_FALSE(remoteType.HasMeta());
+    EXPECT_EQ(remoteType.StringifyMeta(), ""_ns);
+    EXPECT_EQ(remoteType.Stringify(), aString);
+  };
+
+  formatSimple(RemoteType::Kind::Prealloc, "prealloc"_ns);
+  formatSimple(RemoteType::Kind::WebContent, "web"_ns);
+  formatSimple(RemoteType::Kind::File, "file"_ns);
+  formatSimple(RemoteType::Kind::PrivilegedAbout, "privilegedabout"_ns);
+  formatSimple(RemoteType::Kind::PrivilegedMozilla, "privilegedmozilla"_ns);
+  formatSimple(RemoteType::Kind::Extension, "extension"_ns);
+  formatSimple(RemoteType::Kind::Inference, "inference"_ns);
+}
+
+TEST(RemoteTypeTest, FormatCompound)
+{
+  auto formatCompound = [](RemoteType aRemoteType, const nsACString& aKind,
+                           const nsACString& aMeta) {
+    EXPECT_TRUE(aRemoteType.IsKnown());
+    EXPECT_EQ(aRemoteType.StringifyKind(), aKind);
+    EXPECT_TRUE(aRemoteType.HasMeta());
+    EXPECT_EQ(aRemoteType.StringifyMeta(), aMeta);
+    nsCString expected = aKind + "="_ns + aMeta;
+    EXPECT_EQ(aRemoteType.Stringify(), expected);
+  };
+
+  OriginAttributes attrs;
+  attrs.mUserContextId = 2;
+  attrs.mPrivateBrowsingId = 1;
+
+  formatCompound(
+      RemoteType::SharedWeb(attrs).WithDisableJit(true).WithSiteOrigin(
+          "https://example.com"_ns),
+      "webIsolated"_ns,
+      "https://example.com^userContextId=2&privateBrowsingId=1&disableJit=1"_ns);
+
+  formatCompound(RemoteType::SharedWeb({})
+                     .WithSiteOrigin("https://example.com"_ns)
+                     .WithDisableJit(true),
+                 "webIsolated"_ns, "https://example.com^disableJit=1"_ns);
+  formatCompound(
+      RemoteType::SharedWeb({}).WithSiteOrigin("https://example.com"_ns),
+      "webIsolated"_ns, "https://example.com"_ns);
+
+  formatCompound(RemoteType::SharedWeb({}).WithSiteOrigin(
+                     "https://example.com"_ns, RemoteType::Kind::WebCoopCoep),
+                 "webCOOP+COEP"_ns, "https://example.com"_ns);
+  formatCompound(
+      RemoteType::SharedWeb({}).WithSiteOrigin(
+          "https://example.com"_ns, RemoteType::Kind::WebServiceWorker),
+      "webServiceWorker"_ns, "https://example.com"_ns);
+}
+
+TEST(RemoteTypeTest, ParseValid)
+{
+  EXPECT_EQ(RemoteType::Parse(VoidCString()), RemoteType::NotRemote());
+
+  EXPECT_EQ(RemoteType::Parse("prealloc"_ns),
+            RemoteType(RemoteType::Kind::Prealloc));
+  EXPECT_EQ(RemoteType::Parse("file"_ns), RemoteType(RemoteType::Kind::File));
+  EXPECT_EQ(RemoteType::Parse("privilegedabout"_ns),
+            RemoteType(RemoteType::Kind::PrivilegedAbout));
+  EXPECT_EQ(RemoteType::Parse("privilegedmozilla"_ns),
+            RemoteType(RemoteType::Kind::PrivilegedMozilla));
+  EXPECT_EQ(RemoteType::Parse("extension"_ns),
+            RemoteType(RemoteType::Kind::Extension));
+  EXPECT_EQ(RemoteType::Parse("inference"_ns),
+            RemoteType(RemoteType::Kind::Inference));
+
+  EXPECT_EQ(RemoteType::Parse("web"_ns),
+            RemoteType(RemoteType::Kind::WebContent));
+  EXPECT_EQ(RemoteType::Parse("web=^disableJit=1"_ns),
+            RemoteType::SharedWeb({}).WithDisableJit(true));
+  {
+    OriginAttributes attrs;
+    attrs.mUserContextId = 2;
+    attrs.mPrivateBrowsingId = 1;
+    EXPECT_EQ(RemoteType::Parse("web=^userContextId=2&privateBrowsingId=1"_ns),
+              RemoteType::SharedWeb(attrs));
+  }
+  {
+    OriginAttributes attrs;
+    attrs.mGeckoViewSessionContextId = u"session 1"_ns;
+    EXPECT_EQ(RemoteType::Parse("web=^geckoViewUserContextId=session+1"_ns),
+              RemoteType::SharedWeb(attrs));
+  }
+
+  EXPECT_EQ(RemoteType::Parse("webIsolated=https://example.com"_ns),
+            RemoteType::SharedWeb({}).WithSiteOrigin("https://example.com"_ns));
+  EXPECT_EQ(RemoteType::Parse("webCOOP+COEP=https://example.com"_ns),
+            RemoteType::SharedWeb({}).WithSiteOrigin(
+                "https://example.com"_ns, RemoteType::Kind::WebCoopCoep));
+  EXPECT_EQ(RemoteType::Parse("webServiceWorker=https://example.com"_ns),
+            RemoteType::SharedWeb({}).WithSiteOrigin(
+                "https://example.com"_ns, RemoteType::Kind::WebServiceWorker));
+}
+
+TEST(RemoteTypeTest, ParseInvalid)
+{
+  constexpr nsLiteralCString kRemoteTypes[] = {
+      ""_ns,
+      "unknown"_ns,
+      "parent"_ns,
+      "web=^unknown=1"_ns,
+      "web=^disableJit=0"_ns,
+      "web=^disableJit=true"_ns,
+      "web=^userContextId=abc"_ns,
+      "web=^userContextId=1&userContextId=2"_ns,
+      "web=^privateBrowsingId=1&userContextId=2"_ns,
+      "web=https://example.com"_ns,
+      "web=^"_ns,
+      "webIsolated=https://example.com^"_ns,
+      "webIsolated=https://example.com/"_ns,
+      "webIsolated=https://user@example.com"_ns,
+      "webIsolated="_ns,
+      "webCOOP+COEP"_ns,
+      "webServiceWorker"_ns,
+      "file=^userContextId=1"_ns,
+      "privilegedabout=https://example.com"_ns,
+      "privilegedabout=^userContextId=1"_ns,
+  };
+
+  for (const auto& string : kRemoteTypes) {
+    EXPECT_FALSE(RemoteType::Parse(string)) << string;
+  }
+}
+
+}  // namespace mozilla::dom
diff --git a/dom/ipc/gtest/moz.build b/dom/ipc/gtest/moz.build
index 321241cd87c7..da147bc747b8 100644
--- a/dom/ipc/gtest/moz.build
+++ b/dom/ipc/gtest/moz.build
@@ -5,6 +5,7 @@
 UNIFIED_SOURCES += [
     "JSIPCValueTest.cpp",
     "ProcessIsolationTest.cpp",
+    "RemoteTypeTest.cpp",
 ]
 
 include("/ipc/chromium/chromium-config.mozbuild")
diff --git a/dom/ipc/jsactor/JSActorManager.h b/dom/ipc/jsactor/JSActorManager.h
index 18dd9477c79b..3bac8f5a3a87 100644
--- a/dom/ipc/jsactor/JSActorManager.h
+++ b/dom/ipc/jsactor/JSActorManager.h
@@ -8,6 +8,7 @@
 #include "js/TypeDecls.h"
 #include "mozilla/dom/JSActor.h"
 #include "mozilla/dom/JSIPCValue.h"
+#include "mozilla/dom/RemoteType.h"
 #include "nsRefPtrHashtable.h"
 #include "nsString.h"
 
@@ -45,7 +46,7 @@ class JSActorManager : public nsISupports {
   void ReceiveRawMessage(const JSActorMessageMeta& aMetadata,
                          JSIPCValue&& aData, ipc::StructuredCloneData* aStack);
 
-  virtual const nsACString& GetRemoteType() const = 0;
+  virtual const RemoteType& GetRemoteType() const = 0;
 
  protected:
   /**
diff --git a/dom/ipc/jsactor/JSActorService.cpp b/dom/ipc/jsactor/JSActorService.cpp
index 6068090bfd78..30a94d51d848 100644
--- a/dom/ipc/jsactor/JSActorService.cpp
+++ b/dom/ipc/jsactor/JSActorService.cpp
@@ -359,41 +359,26 @@ JSActorService::GetJSWindowActorProtocol(const nsACString& aName) {
   return mWindowActorDescriptors.Get(aName);
 }
 
-static nsDependentCSubstring RemoteTypePrefixForMatch(
-    const nsACString& aRemoteType) {
-  nsDependentCSubstring remoteTypePrefix(RemoteTypePrefix(aRemoteType));
-  // The actual remote type for the parent process is the empty string, so
-  // change it to something we can actually match.
-  MOZ_ASSERT(!StringBeginsWith(remoteTypePrefix, "parent"_ns));
-  if (aRemoteType == NOT_REMOTE_TYPE) {
-    remoteTypePrefix.AssignLiteral("parent");
-  }
-  return remoteTypePrefix;
-}
-
-void JSActorProtocol::LogMatch(const nsACString& aRemoteType) {
+void JSActorProtocol::LogMatch(const RemoteType& aRemoteType) {
   if (!MOZ_LOG_TEST(gJSActorServiceLog, LogLevel::Info)) {
     return;
   }
 
-  nsDependentCSubstring remoteTypePrefix(RemoteTypePrefixForMatch(aRemoteType));
-  if (mLoggedRemoteTypes.Contains(remoteTypePrefix)) {
+  nsCString remoteTypeKind(aRemoteType.StringifyKind());
+  if (mLoggedRemoteTypes.Contains(remoteTypeKind)) {
     return;
   }
 
-  mLoggedRemoteTypes.AppendElement(remoteTypePrefix);
+  mLoggedRemoteTypes.AppendElement(remoteTypeKind);
   MOZ_LOG_FMT(gJSActorServiceLog, LogLevel::Info,
               "JSActor '{}' matched remoteType '{}'", mName.get(),
-              PromiseFlatCString(remoteTypePrefix).get());
+              remoteTypeKind.get());
 }
 
-bool JSActorProtocol::RemoteTypePrefixMatches(const nsACString& aRemoteType) {
-  nsDependentCSubstring remoteTypePrefix(RemoteTypePrefixForMatch(aRemoteType));
-
+bool JSActorProtocol::RemoteTypeMatches(const RemoteType& aRemoteType) {
   if (StaticPrefs::dom_jsipc_check_safeForUntrustedWebProcess() &&
       !mSafeForUntrustedWebProcess &&
-      (StringBeginsWith(remoteTypePrefix, "web"_ns) ||
-       StringBeginsWith(remoteTypePrefix, "file"_ns))) {
+      (aRemoteType.IsWeb() || aRemoteType.IsFile())) {
     return false;
   }
 
@@ -401,9 +386,12 @@ bool JSActorProtocol::RemoteTypePrefixMatches(const nsACString& aRemoteType) {
     return true;
   }
 
+  // TODO: Consider using a more advanced matcher which is aware of the
+  // structure of RemoteType. See bug 2006165.
+  nsCString remoteTypeKind(aRemoteType.StringifyKind());
+
   for (auto& remoteType : mRemoteTypes) {
-    // TODO: Maybe this should use glob-style matching instead. See bug 2006165.
-    if (StringBeginsWith(remoteTypePrefix, remoteType)) {
+    if (StringBeginsWith(remoteTypeKind, remoteType)) {
       return true;
     }
   }
diff --git a/dom/ipc/jsactor/JSActorService.h b/dom/ipc/jsactor/JSActorService.h
index eec09dbdb63f..bb4b63e4e079 100644
--- a/dom/ipc/jsactor/JSActorService.h
+++ b/dom/ipc/jsactor/JSActorService.h
@@ -105,8 +105,8 @@ class JSActorProtocol : public nsISupports {
 
  protected:
   explicit JSActorProtocol(const nsACString& aName) : mName(aName) {}
-  void LogMatch(const nsACString& aRemoteType);
-  bool RemoteTypePrefixMatches(const nsACString& aRemoteType);
+  void LogMatch(const RemoteType& aRemoteType);
+  bool RemoteTypeMatches(const RemoteType& aRemoteType);
 
   nsCString mName;
   nsTArray<nsCString> mRemoteTypes;
diff --git a/dom/ipc/jsactor/JSProcessActorProtocol.cpp b/dom/ipc/jsactor/JSProcessActorProtocol.cpp
index 08679cf7080a..c8cb60495ac2 100644
--- a/dom/ipc/jsactor/JSProcessActorProtocol.cpp
+++ b/dom/ipc/jsactor/JSProcessActorProtocol.cpp
@@ -114,18 +114,18 @@ void JSProcessActorProtocol::RemoveObservers() {
   }
 }
 
-bool JSProcessActorProtocol::Matches(const nsACString& aRemoteType,
+bool JSProcessActorProtocol::Matches(const RemoteType& aRemoteType,
                                      ErrorResult& aRv) {
-  if (!mIncludeParent && aRemoteType.IsEmpty()) {
+  if (!mIncludeParent && aRemoteType.IsNotRemote()) {
     aRv.ThrowNotSupportedError(nsPrintfCString(
         "Process protocol '%s' doesn't match the parent process", mName.get()));
     return false;
   }
 
-  if (!RemoteTypePrefixMatches(aRemoteType)) {
+  if (!RemoteTypeMatches(aRemoteType)) {
     aRv.ThrowNotSupportedError(nsPrintfCString(
         "Process protocol '%s' doesn't support remote type '%s'", mName.get(),
-        PromiseFlatCString(aRemoteType).get()));
+        aRemoteType.Stringify().get()));
     return false;
   }
 
diff --git a/dom/ipc/jsactor/JSProcessActorProtocol.h b/dom/ipc/jsactor/JSProcessActorProtocol.h
index 9f1eb630a030..907ced906042 100644
--- a/dom/ipc/jsactor/JSProcessActorProtocol.h
+++ b/dom/ipc/jsactor/JSProcessActorProtocol.h
@@ -53,7 +53,7 @@ class JSProcessActorProtocol final : public JSActorProtocol,
 
   void AddObservers();
   void RemoveObservers();
-  bool Matches(const nsACString& aRemoteType, ErrorResult& aRv);
+  bool Matches(const RemoteType& aRemoteType, ErrorResult& aRv);
 
  private:
   explicit JSProcessActorProtocol(const nsACString& aName)
diff --git a/dom/ipc/jsactor/JSWindowActorProtocol.cpp b/dom/ipc/jsactor/JSWindowActorProtocol.cpp
index e64be334ea88..c672047f1a24 100644
--- a/dom/ipc/jsactor/JSWindowActorProtocol.cpp
+++ b/dom/ipc/jsactor/JSWindowActorProtocol.cpp
@@ -318,7 +318,7 @@ bool JSWindowActorProtocol::MessageManagerGroupMatches(
 }
 
 bool JSWindowActorProtocol::Matches(BrowsingContext* aBrowsingContext,
-                                    nsIURI* aURI, const nsACString& aRemoteType,
+                                    nsIURI* aURI, const RemoteType& aRemoteType,
                                     ErrorResult& aRv) {
   MOZ_ASSERT(aBrowsingContext, "DocShell without a BrowsingContext!");
   MOZ_ASSERT(aURI, "Must have URI!");
@@ -336,10 +336,10 @@ bool JSWindowActorProtocol::Matches(BrowsingContext* aBrowsingContext,
     return false;
   }
 
-  if (!RemoteTypePrefixMatches(aRemoteType)) {
+  if (!RemoteTypeMatches(aRemoteType)) {
     aRv.ThrowNotSupportedError(
         nsPrintfCString("Window protocol '%s' doesn't match remote type '%s'",
-                        mName.get(), PromiseFlatCString(aRemoteType).get()));
+                        mName.get(), aRemoteType.Stringify().get()));
     return false;
   }
 
diff --git a/dom/ipc/jsactor/JSWindowActorProtocol.h b/dom/ipc/jsactor/JSWindowActorProtocol.h
index c233242f8e61..6e8df9bc4d93 100644
--- a/dom/ipc/jsactor/JSWindowActorProtocol.h
+++ b/dom/ipc/jsactor/JSWindowActorProtocol.h
@@ -71,7 +71,7 @@ class JSWindowActorProtocol final : public JSActorProtocol,
   void AddObservers();
   void RemoveObservers();
   bool Matches(BrowsingContext* aBrowsingContext, nsIURI* aURI,
-               const nsACString& aRemoteType, ErrorResult& aRv);
+               const RemoteType& aRemoteType, ErrorResult& aRv);
 
  private:
   explicit JSWindowActorProtocol(const nsACString& aName)
diff --git a/dom/ipc/moz.build b/dom/ipc/moz.build
index c149627f819e..58c9e15a4b66 100644
--- a/dom/ipc/moz.build
+++ b/dom/ipc/moz.build
@@ -157,6 +157,7 @@ UNIFIED_SOURCES += [
     "ReferrerInfoUtils.cpp",
     "RefMessageBodyService.cpp",
     "RemoteBrowser.cpp",
+    "RemoteType.cpp",
     "RemoteWebProgressRequest.cpp",
     "SharedMap.cpp",
     "SharedMessageBody.cpp",
diff --git a/dom/ipc/tests/test_headless_content_process.js b/dom/ipc/tests/test_headless_content_process.js
index 28d9f60be370..fedf792cd67b 100644
--- a/dom/ipc/tests/test_headless_content_process.js
+++ b/dom/ipc/tests/test_headless_content_process.js
@@ -1,6 +1,6 @@
 "use strict";
 
-const TEST_REMOTE_TYPE = "test";
+const TEST_REMOTE_TYPE = "inference";
 
 function allTestProcs() {
   return ChromeUtils.getAllDOMProcesses().filter(
diff --git a/dom/media/gmp/GMPProcessParent.cpp b/dom/media/gmp/GMPProcessParent.cpp
index 62505b9e16a4..a90181e3e6d8 100644
--- a/dom/media/gmp/GMPProcessParent.cpp
+++ b/dom/media/gmp/GMPProcessParent.cpp
@@ -90,7 +90,7 @@ bool GMPProcessParent::Launch(int32_t aTimeoutMs) {
       auto prefSerializer = MakeUnique<ipc::SharedPreferenceSerializer>();
       bool success =
           prefSerializer->SerializeToSharedMemory(GeckoProcessType_GMPlugin,
-                                                  /* remoteType */ ""_ns);
+                                                  /* remoteType */ {});
 
       MonitorAutoLock lock(mMonitor);
       MOZ_ASSERT(!mComplete);
diff --git a/dom/media/gmp/GMPServiceParent.cpp b/dom/media/gmp/GMPServiceParent.cpp
index d24fa8a33062..c4f6c5d71173 100644
--- a/dom/media/gmp/GMPServiceParent.cpp
+++ b/dom/media/gmp/GMPServiceParent.cpp
@@ -365,7 +365,7 @@ GeckoMediaPluginServiceParent::Observe(nsISupports* aSubject,
       mozilla::dom::Pref pref(strData, /* isLocked */ false,
                               /* isSanitized */ false, Nothing(), Nothing());
       Preferences::GetPreference(&pref, GeckoProcessType_GMPlugin,
-                                 /* remoteType */ ""_ns);
+                                 /* remoteType */ {});
       return GMPDispatch(NewRunnableMethod<mozilla::dom::Pref&&>(
           "gmp::GeckoMediaPluginServiceParent::OnPreferenceChanged", this,
           &GeckoMediaPluginServiceParent::OnPreferenceChanged,
diff --git a/dom/media/ipc/RDDProcessHost.cpp b/dom/media/ipc/RDDProcessHost.cpp
index 93ffedfc5dee..292d8f136ce2 100644
--- a/dom/media/ipc/RDDProcessHost.cpp
+++ b/dom/media/ipc/RDDProcessHost.cpp
@@ -46,7 +46,7 @@ bool RDDProcessHost::Launch(geckoargs::ChildProcessArgs aExtraOpts) {
 
   mPrefSerializer = MakeUnique<ipc::SharedPreferenceSerializer>();
   if (!mPrefSerializer->SerializeToSharedMemory(GeckoProcessType_RDD,
-                                                /* remoteType */ ""_ns)) {
+                                                /* remoteType */ {})) {
     return false;
   }
   mPrefSerializer->AddSharedPrefCmdLineArgs(*this, aExtraOpts);
diff --git a/dom/media/ipc/RDDProcessManager.cpp b/dom/media/ipc/RDDProcessManager.cpp
index 8b5a85e7987f..c1bc89d03320 100644
--- a/dom/media/ipc/RDDProcessManager.cpp
+++ b/dom/media/ipc/RDDProcessManager.cpp
@@ -104,7 +104,7 @@ void RDDProcessManager::OnPreferenceChange(const char16_t* aData) {
                           /* isSanitized */ false, Nothing(), Nothing());
 
   Preferences::GetPreference(&pref, GeckoProcessType_RDD,
-                             /* remoteType */ ""_ns);
+                             /* remoteType */ {});
   if (!!mRDDChild) {
     MOZ_ASSERT(mQueuedPrefs.IsEmpty());
     mRDDChild->SendPreferenceUpdate(pref);
diff --git a/dom/media/webrtc/transport/ipc/WebrtcTCPSocket.cpp b/dom/media/webrtc/transport/ipc/WebrtcTCPSocket.cpp
index 3dda7ca38aa4..28458bedcd1b 100644
--- a/dom/media/webrtc/transport/ipc/WebrtcTCPSocket.cpp
+++ b/dom/media/webrtc/transport/ipc/WebrtcTCPSocket.cpp
@@ -401,13 +401,14 @@ nsresult WebrtcTCPSocket::OpenWithHttpProxy() {
   nsCOMPtr<nsILoadInfo> loadInfo;
 
   // FIXME: We don't know the remote type of the process which provided these
-  // LoadInfoArgs. Pass in `NOT_REMOTE_TYPE` as the origin process to blindly
-  // accept whatever value was passed by the other side for now, as we aren't
-  // using it for security checks here.
+  // LoadInfoArgs. Pass in `RemoteType::NotRemote()` as the origin process to
+  // blindly accept whatever value was passed by the other side for now, as we
+  // aren't using it for security checks here.
   // If this code ever starts checking the triggering remote type, this needs to
   // be changed.
   rv = ipc::LoadInfoArgsToLoadInfo(mProxyConfig->loadInfoArgs(),
-                                   NOT_REMOTE_TYPE, getter_AddRefs(loadInfo));
+                                   dom::RemoteType::NotRemote(),
+                                   getter_AddRefs(loadInfo));
   if (NS_FAILED(rv)) {
     LOG("WebrtcTCPSocket {}: could not init load info\n", fmt::ptr(this));
     return rv;
diff --git a/dom/onnx/InferenceSession.cpp b/dom/onnx/InferenceSession.cpp
index 8d8b7fc889c8..5087d5c4623f 100644
--- a/dom/onnx/InferenceSession.cpp
+++ b/dom/onnx/InferenceSession.cpp
@@ -240,8 +240,7 @@ bool InferenceSession::InInferenceProcess(JSContext*, JSObject*) {
   if (!ContentChild::GetSingleton()) {
     return false;
   }
-  return ContentChild::GetSingleton()->GetRemoteType().Equals(
-      INFERENCE_REMOTE_TYPE);
+  return ContentChild::GetSingleton()->GetRemoteType().IsInference();
 }
 
 bool InferenceSession::IsAvailable(const GlobalObject&) {
diff --git a/dom/security/nsContentSecurityManager.cpp b/dom/security/nsContentSecurityManager.cpp
index 42df7cce44c6..2464d8374286 100644
--- a/dom/security/nsContentSecurityManager.cpp
+++ b/dom/security/nsContentSecurityManager.cpp
@@ -690,7 +690,7 @@ static void DebugDoContentSecurityCheck(nsIChannel* aChannel,
   if (httpChannel || MOZ_LOG_TEST(sCSMLog, LogLevel::Verbose)) {
     MOZ_LOG(sCSMLog, LogLevel::Verbose, ("doContentSecurityCheck:\n"));
 
-    nsAutoCString remoteType;
+    RemoteType remoteType;
     if (XRE_IsParentProcess()) {
       nsCOMPtr<nsIParentChannel> parentChannel;
       NS_QueryNotificationCallbacks(aChannel, parentChannel);
@@ -698,11 +698,10 @@ static void DebugDoContentSecurityCheck(nsIChannel* aChannel,
         parentChannel->GetRemoteType(remoteType);
       }
     } else {
-      remoteType.Assign(
-          mozilla::dom::ContentChild::GetSingleton()->GetRemoteType());
+      remoteType = mozilla::dom::ContentChild::GetSingleton()->GetRemoteType();
     }
     MOZ_LOG(sCSMLog, LogLevel::Verbose,
-            ("  processType: \"%s\"\n", remoteType.get()));
+            ("  processType: \"%s\"\n", remoteType.Stringify().get()));
 
     nsCOMPtr<nsIURI> channelURI;
     nsAutoCString channelSpec;
@@ -790,7 +789,7 @@ static void DebugDoContentSecurityCheck(nsIChannel* aChannel,
 
 /* static */
 void nsContentSecurityManager::MeasureUnexpectedPrivilegedLoads(
-    nsILoadInfo* aLoadInfo, nsIURI* aFinalURI, const nsACString& aRemoteType) {
+    nsILoadInfo* aLoadInfo, nsIURI* aFinalURI, const RemoteType& aRemoteType) {
   if (!StaticPrefs::dom_security_unexpected_system_load_telemetry_enabled()) {
     return;
   }
@@ -845,9 +844,10 @@ void nsContentSecurityManager::MeasureUnexpectedPrivilegedLoads(
   if (fileNameTypeAndDetails.second.isSome()) {
     loggedFileDetails.Assign(fileNameTypeAndDetails.second.value());
   }
-  // sanitize remoteType because it may contain sensitive
-  // info, like URLs. e.g. `webIsolated=https://example.com`
-  nsAutoCString loggedRemoteType(dom::RemoteTypePrefix(aRemoteType));
+  // We only include the kind part of the remote type, as the rest of the
+  // remote type may contain sensitive information like URLs. e.g.
+  // `webIsolated=https://example.com`
+  nsCString loggedRemoteType = aRemoteType.StringifyKind();
   nsAutoCString loggedContentType(NS_CP_ContentTypeName(contentPolicyType));
 
   MOZ_LOG(sUELLog, LogLevel::Debug, ("UnexpectedPrivilegedLoadTelemetry:\n"));
@@ -995,7 +995,7 @@ nsresult nsContentSecurityManager::CheckAllowLoadInSystemPrivilegedContext(
   // URI_IS_UI_RESOURCE, first remove layers of view-source:, if present.
   nsCOMPtr<nsIURI> innerURI = NS_GetInnermostURI(finalURI);
 
-  nsAutoCString remoteType;
+  RemoteType remoteType;
   if (XRE_IsParentProcess()) {
     nsCOMPtr<nsIParentChannel> parentChannel;
     NS_QueryNotificationCallbacks(aChannel, parentChannel);
@@ -1003,8 +1003,7 @@ nsresult nsContentSecurityManager::CheckAllowLoadInSystemPrivilegedContext(
       parentChannel->GetRemoteType(remoteType);
     }
   } else {
-    remoteType.Assign(
-        mozilla::dom::ContentChild::GetSingleton()->GetRemoteType());
+    remoteType = mozilla::dom::ContentChild::GetSingleton()->GetRemoteType();
   }
 
   // GetInnerURI can return null for malformed nested URIs like moz-icon:trash
@@ -1113,7 +1112,7 @@ nsresult nsContentSecurityManager::CheckAllowLoadInPrivilegedAboutContext(
     return NS_OK;
   }
 
-  nsAutoCString remoteType;
+  RemoteType remoteType;
   if (XRE_IsParentProcess()) {
     nsCOMPtr<nsIParentChannel> parentChannel;
     NS_QueryNotificationCallbacks(aChannel, parentChannel);
@@ -1121,12 +1120,11 @@ nsresult nsContentSecurityManager::CheckAllowLoadInPrivilegedAboutContext(
       parentChannel->GetRemoteType(remoteType);
     }
   } else {
-    remoteType.Assign(
-        mozilla::dom::ContentChild::GetSingleton()->GetRemoteType());
+    remoteType = mozilla::dom::ContentChild::GetSingleton()->GetRemoteType();
   }
 
   // only perform check for privileged about process
-  if (!remoteType.Equals(PRIVILEGEDABOUT_REMOTE_TYPE)) {
+  if (!remoteType.IsPrivilegedAbout()) {
     return NS_OK;
   }
 
@@ -1332,7 +1330,7 @@ static nsresult CheckAllowLoadByTriggeringRemoteType(nsIChannel* aChannel) {
 
   nsCOMPtr<nsILoadInfo> loadInfo = aChannel->LoadInfo();
 
-  nsAutoCString triggeringRemoteType;
+  RemoteType triggeringRemoteType;
   nsresult rv = loadInfo->GetTriggeringRemoteType(triggeringRemoteType);
   NS_ENSURE_SUCCESS(rv, rv);
 
@@ -1347,7 +1345,7 @@ static nsresult CheckAllowLoadByTriggeringRemoteType(nsIChannel* aChannel) {
       loadInfo->PrincipalToInherit()->GetOrigin(origin);
       MOZ_LOG(sUELLog, LogLevel::Warning,
               ("Unexpected PrincipalToInherit %s for remote %s", origin.get(),
-               triggeringRemoteType.get()));
+               triggeringRemoteType.Stringify().get()));
     }
     return NS_ERROR_CONTENT_BLOCKED;
   }
@@ -1368,7 +1366,7 @@ static nsresult CheckAllowLoadByTriggeringRemoteType(nsIChannel* aChannel) {
 
   // For now, only restrict loads coming from web remote types. In the future we
   // may want to expand this a bit.
-  if (!StringBeginsWith(triggeringRemoteType, WEB_REMOTE_TYPE)) {
+  if (!triggeringRemoteType.IsWeb()) {
     return NS_OK;
   }
 
@@ -1808,12 +1806,12 @@ nsresult nsContentSecurityManager::CheckForIncoherentResultPrincipal(
       return NS_ERROR_CONTENT_BLOCKED;
     }
 
-    nsAutoCString triggeringRemoteType;
+    RemoteType triggeringRemoteType;
     rv = loadInfo->GetTriggeringRemoteType(triggeringRemoteType);
     NS_ENSURE_SUCCESS(rv, rv);
 
-    if (triggeringRemoteType != NOT_REMOTE_TYPE &&
-        triggeringRemoteType != EXTENSION_REMOTE_TYPE) {
+    if (!triggeringRemoteType.IsNotRemote() &&
+        !triggeringRemoteType.IsExtension()) {
       MOZ_ASSERT_UNREACHABLE(
           "Generated addon background page in incorrect process");
       return NS_ERROR_CONTENT_BLOCKED;
diff --git a/dom/security/nsContentSecurityManager.h b/dom/security/nsContentSecurityManager.h
index 854dca5fb0e5..d667890157d4 100644
--- a/dom/security/nsContentSecurityManager.h
+++ b/dom/security/nsContentSecurityManager.h
@@ -36,9 +36,9 @@ class nsContentSecurityManager : public nsIContentSecurityManager,
   static void ReportBlockedDataURI(nsIURI* aURI, nsILoadInfo* aLoadInfo,
                                    bool aIsRedirect = false);
   static bool AllowInsecureRedirectToDataURI(nsIChannel* aNewChannel);
-  static void MeasureUnexpectedPrivilegedLoads(nsILoadInfo* aLoadInfo,
-                                               nsIURI* aFinalURI,
-                                               const nsACString& aRemoteType);
+  static void MeasureUnexpectedPrivilegedLoads(
+      nsILoadInfo* aLoadInfo, nsIURI* aFinalURI,
+      const mozilla::dom::RemoteType& aRemoteType);
 
   enum CORSSecurityMapping {
     // Disables all CORS checking overriding the value of aCORSMode. All checks
diff --git a/dom/security/test/gtest/TestUnexpectedPrivilegedLoads.cpp b/dom/security/test/gtest/TestUnexpectedPrivilegedLoads.cpp
index db1b5197283e..a94353534c4f 100644
--- a/dom/security/test/gtest/TestUnexpectedPrivilegedLoads.cpp
+++ b/dom/security/test/gtest/TestUnexpectedPrivilegedLoads.cpp
@@ -80,7 +80,7 @@ TEST_F(TelemetryTestFixture, UnexpectedPrivilegedLoadsTelemetryTest) {
        // ..and test that we strip of URLs from remoteTypes
        "blob://000-000"_ns,
        nsContentPolicyType::TYPE_SCRIPT,
-       "webIsolated=https://blob.example/"_ns,
+       "webIsolated=https://blob.example"_ns,
        {"bloburi"_ns, "TYPE_SCRIPT"_ns, "webIsolated"_ns, "unknown"_ns, ""_ns}},
       {// test for cases where finalURI is null, due to a broken nested URI
        // .. like malformed moz-icon URLs
@@ -195,9 +195,12 @@ TEST_F(TelemetryTestFixture, UnexpectedPrivilegedLoadsTelemetryTest) {
       mockLoadInfo->AppendRedirectHistoryEntry(redirectChannel, false);
     }
 
+    auto remoteType = mozilla::dom::RemoteType::Parse(currentTest.remoteType);
+    ASSERT_TRUE(remoteType);
+
     // this will record the event
-    nsContentSecurityManager::MeasureUnexpectedPrivilegedLoads(
-        mockLoadInfo, uri, currentTest.remoteType);
+    nsContentSecurityManager::MeasureUnexpectedPrivilegedLoads(mockLoadInfo,
+                                                               uri, remoteType);
 
     // let's inspect the recorded Glean events
     auto optEvents =
diff --git a/dom/serviceworkers/ServiceWorkerPrivate.cpp b/dom/serviceworkers/ServiceWorkerPrivate.cpp
index 63927bf28a58..7ca4c228ee3e 100644
--- a/dom/serviceworkers/ServiceWorkerPrivate.cpp
+++ b/dom/serviceworkers/ServiceWorkerPrivate.cpp
@@ -729,7 +729,7 @@ nsresult ServiceWorkerPrivate::Initialize() {
 
   auto remoteType = RemoteWorkerManager::GetRemoteType(
       principal, WorkerKind::WorkerKindService,
-      SharedWebRemoteType(principal->OriginAttributesRef()));
+      RemoteType::SharedWeb(principal->OriginAttributesRef()));
   if (NS_WARN_IF(remoteType.isErr())) {
     return remoteType.unwrapErr();
   }
@@ -1816,8 +1816,7 @@ void ServiceWorkerPrivate::CreationFailed() {
   MOZ_ASSERT(NS_IsMainThread());
   MOZ_ASSERT(mControllerChild);
 
-  if (mRemoteWorkerData.remoteType().Find(SERVICEWORKER_REMOTE_TYPE) !=
-      kNotFound) {
+  if (mRemoteWorkerData.remoteType().IsWebServiceWorker()) {
     glean::service_worker::isolated_launch_time.AccumulateRawDuration(
         TimeStamp::Now() - mServiceWorkerLaunchTimeStart);
   } else {
@@ -1843,8 +1842,7 @@ void ServiceWorkerPrivate::CreationSucceeded() {
     return;
   }
 
-  if (mRemoteWorkerData.remoteType().Find(SERVICEWORKER_REMOTE_TYPE) !=
-      kNotFound) {
+  if (mRemoteWorkerData.remoteType().IsWebServiceWorker()) {
     glean::service_worker::isolated_launch_time.AccumulateRawDuration(
         TimeStamp::Now() - mServiceWorkerLaunchTimeStart);
   } else {
diff --git a/dom/workers/remoteworkers/RemoteWorkerManager.cpp b/dom/workers/remoteworkers/RemoteWorkerManager.cpp
index 67de2191e39b..c2ac93567466 100644
--- a/dom/workers/remoteworkers/RemoteWorkerManager.cpp
+++ b/dom/workers/remoteworkers/RemoteWorkerManager.cpp
@@ -84,11 +84,11 @@ void TransmitPermissionsAndCookiesAndBlobURLsForPrincipalInfo(
 }  // namespace
 
 // static
-bool RemoteWorkerManager::MatchRemoteType(const nsACString& processRemoteType,
-                                          const nsACString& workerRemoteType) {
+bool RemoteWorkerManager::MatchRemoteType(const RemoteType& processRemoteType,
+                                          const RemoteType& workerRemoteType) {
   LOG(("MatchRemoteType [processRemoteType=%s, workerRemoteType=%s]",
-       PromiseFlatCString(processRemoteType).get(),
-       PromiseFlatCString(workerRemoteType).get()));
+       processRemoteType.Stringify().get(),
+       workerRemoteType.Stringify().get()));
 
   // Respecting COOP and COEP requires processing headers in the parent
   // process in order to choose an appropriate content process, but the
@@ -102,15 +102,15 @@ bool RemoteWorkerManager::MatchRemoteType(const nsACString& processRemoteType,
   // RemoteWorkerManager::GetRemoteType should not select this remoteType
   // and so workerRemoteType is not expected to be set to a coop+coep
   // remoteType and here we can just assert that it is not happening.
-  MOZ_ASSERT(!IsWebCoopCoepRemoteType(workerRemoteType));
+  MOZ_ASSERT(!workerRemoteType.IsWebCoopCoep());
 
-  return processRemoteType.Equals(workerRemoteType);
+  return processRemoteType == workerRemoteType;
 }
 
 // static
-Result<nsCString, nsresult> RemoteWorkerManager::GetRemoteType(
+Result<RemoteType, nsresult> RemoteWorkerManager::GetRemoteType(
     const nsCOMPtr<nsIPrincipal>& aPrincipal, WorkerKind aWorkerKind,
-    const nsACString& aCurrentRemoteType) {
+    const RemoteType& aCurrentRemoteType) {
   AssertIsOnMainThread();
 
   MOZ_ASSERT_IF(aWorkerKind == WorkerKind::WorkerKindService,
@@ -120,7 +120,7 @@ Result<nsCString, nsresult> RemoteWorkerManager::GetRemoteType(
   // to finish the load in the parent process.
   if (!BrowserTabsRemoteAutostart()) {
     LOG(("GetRemoteType: Loading in parent process as e10s is disabled"));
-    return NOT_REMOTE_TYPE;
+    return RemoteType::NotRemote();
   }
 
   auto result = IsolationOptionsForWorker(
@@ -139,8 +139,8 @@ Result<nsCString, nsresult> RemoteWorkerManager::GetRemoteType(
         ("GetRemoteType workerType=%s, principal=%s, "
          "preferredRemoteType=%s, selectedRemoteType=%s",
          aWorkerKind == WorkerKind::WorkerKindService ? "service" : "shared",
-         principalOrigin.get(), PromiseFlatCString(aCurrentRemoteType).get(),
-         options.mRemoteType.get()));
+         principalOrigin.get(), aCurrentRemoteType.Stringify().get(),
+         options.mRemoteType.Stringify().get()));
   }
 
   return options.mRemoteType;
@@ -326,7 +326,7 @@ void RemoteWorkerManager::AsyncCreationFailed(
 
 template <typename Callback>
 void RemoteWorkerManager::ForEachActor(
-    Callback&& aCallback, const nsACString& aRemoteType,
+    Callback&& aCallback, const RemoteType& aRemoteType,
     Maybe<base::ProcessId> aProcessId) const {
   AssertIsOnBackgroundThread();
 
@@ -431,7 +431,7 @@ RemoteWorkerManager::SelectTargetActor(const RemoteWorkerData& aData,
   // Extension principal workers are allowed to run on the parent process
   // when "extensions.webextensions.remote" pref is false.
   if (aProcessId == base::GetCurrentProcId() &&
-      aData.remoteType().Equals(NOT_REMOTE_TYPE) &&
+      aData.remoteType().IsNotRemote() &&
       !StaticPrefs::extensions_webextensions_remote() &&
       HasExtensionPrincipal(aData)) {
     MOZ_ASSERT(mParentActor);
diff --git a/dom/workers/remoteworkers/RemoteWorkerManager.h b/dom/workers/remoteworkers/RemoteWorkerManager.h
index d61e120ab153..01fbe3c37b67 100644
--- a/dom/workers/remoteworkers/RemoteWorkerManager.h
+++ b/dom/workers/remoteworkers/RemoteWorkerManager.h
@@ -38,16 +38,16 @@ class RemoteWorkerManager final {
   void Launch(RemoteWorkerController* aController,
               const RemoteWorkerData& aData, base::ProcessId aProcessId);
 
-  static bool MatchRemoteType(const nsACString& processRemoteType,
-                              const nsACString& workerRemoteType);
+  static bool MatchRemoteType(const RemoteType& processRemoteType,
+                              const RemoteType& workerRemoteType);
 
   /**
    * Get the child process RemoteType where a RemoteWorker should be
    * launched.
    */
-  static Result<nsCString, nsresult> GetRemoteType(
+  static Result<RemoteType, nsresult> GetRemoteType(
       const nsCOMPtr<nsIPrincipal>& aPrincipal, WorkerKind aWorkerKind,
-      const nsACString& aCurrentRemoteType);
+      const RemoteType& aCurrentRemoteType);
 
   static bool HasExtensionPrincipal(const RemoteWorkerData& aData);
 
@@ -93,7 +93,7 @@ class RemoteWorkerManager final {
   // doesn't need to worry about proxy-releasing the ContentParent if it isn't
   // moved out of the parameter.
   template <typename Callback>
-  void ForEachActor(Callback&& aCallback, const nsACString& aRemoteType,
+  void ForEachActor(Callback&& aCallback, const RemoteType& aRemoteType,
                     Maybe<base::ProcessId> aProcessId = Nothing()) const;
 
   // The list of existing RemoteWorkerServiceParent actors for child processes.
diff --git a/dom/workers/remoteworkers/RemoteWorkerServiceParent.cpp b/dom/workers/remoteworkers/RemoteWorkerServiceParent.cpp
index 422671c34744..9ede7a2fd80f 100644
--- a/dom/workers/remoteworkers/RemoteWorkerServiceParent.cpp
+++ b/dom/workers/remoteworkers/RemoteWorkerServiceParent.cpp
@@ -70,11 +70,11 @@ void RemoteWorkerServiceParent::ActorDestroy(IProtocol::ActorDestroyReason) {
   }
 }
 
-nsCString RemoteWorkerServiceParent::GetRemoteType() const {
+RemoteType RemoteWorkerServiceParent::GetRemoteType() const {
   if (mProcess) {
     return mProcess->GetRemoteType();
   }
-  return NOT_REMOTE_TYPE;
+  return RemoteType::NotRemote();
 }
 
 }  // namespace dom
diff --git a/dom/workers/remoteworkers/RemoteWorkerServiceParent.h b/dom/workers/remoteworkers/RemoteWorkerServiceParent.h
index eecfb7dcadfe..7c0261e4355c 100644
--- a/dom/workers/remoteworkers/RemoteWorkerServiceParent.h
+++ b/dom/workers/remoteworkers/RemoteWorkerServiceParent.h
@@ -33,7 +33,7 @@ class RemoteWorkerServiceParent final : public PRemoteWorkerServiceParent {
     return mProcess;
   }
 
-  nsCString GetRemoteType() const;
+  RemoteType GetRemoteType() const;
 
  private:
   explicit RemoteWorkerServiceParent(ThreadsafeContentParentHandle* aProcess);
diff --git a/dom/workers/remoteworkers/RemoteWorkerTypes.ipdlh b/dom/workers/remoteworkers/RemoteWorkerTypes.ipdlh
index f17323a39fc0..ababf915edff 100644
--- a/dom/workers/remoteworkers/RemoteWorkerTypes.ipdlh
+++ b/dom/workers/remoteworkers/RemoteWorkerTypes.ipdlh
@@ -20,6 +20,7 @@ using mozilla::dom::WorkerOptions from "mozilla/dom/WorkerBinding.h";
 using mozilla::StorageAccess from "mozilla/StorageAccess.h";
 using mozilla::OriginTrials from "mozilla/OriginTrialsIPCUtils.h";
 using mozilla::RFPTargetSet from "nsRFPService.h";
+using struct mozilla::dom::RemoteType from "mozilla/dom/RemoteType.h";
 
 [RefCounted] using class nsIPrincipal from "nsIPrincipal.h";
 
@@ -99,7 +100,7 @@ struct RemoteWorkerData
   nsID agentClusterId;
 
   // Child process remote type where the worker should only run on.
-  nsCString remoteType;
+  RemoteType remoteType;
 
   nsCString languageOverrideLocale;
   nsString[] languageOverride;
diff --git a/dom/workers/sharedworkers/SharedWorker.cpp b/dom/workers/sharedworkers/SharedWorker.cpp
index 18c047efea7e..764b90902b5a 100644
--- a/dom/workers/sharedworkers/SharedWorker.cpp
+++ b/dom/workers/sharedworkers/SharedWorker.cpp
@@ -274,8 +274,9 @@ already_AddRefed<SharedWorker> SharedWorker::Constructor(
       loadInfo.mIsOn3PCBExceptionList,
       OriginTrials::FromWindow(nsGlobalWindowInner::Cast(window)),
       void_t() /* OptionalServiceWorkerData */, agentClusterId,
-      DEFAULT_REMOTE_TYPE /* ignored */, loadInfo.mLanguageOverrideLocale,
-      loadInfo.mLanguageOverride.Clone(), loadInfo.mTimezoneOverride);
+      RemoteType(RemoteType::Kind::WebContent) /* ignored */,
+      loadInfo.mLanguageOverrideLocale, loadInfo.mLanguageOverride.Clone(),
+      loadInfo.mTimezoneOverride);
 
   PSharedWorkerChild* pActor = actorChild->SendPSharedWorkerConstructor(
       remoteWorkerData, loadInfo.mWindowID, portIdentifier.release());
diff --git a/dom/workers/sharedworkers/SharedWorkerService.cpp b/dom/workers/sharedworkers/SharedWorkerService.cpp
index 9e569c322bab..c5bf929691ab 100644
--- a/dom/workers/sharedworkers/SharedWorkerService.cpp
+++ b/dom/workers/sharedworkers/SharedWorkerService.cpp
@@ -236,7 +236,7 @@ void SharedWorkerService::GetOrCreateWorkerManagerOnMainThread(
   // the ununsed remoteType field from the passed-in `RemoteWorkerData` with it.
   auto remoteType = RemoteWorkerManager::GetRemoteType(
       principal, WorkerKind::WorkerKindShared,
-      contentParent ? contentParent->GetRemoteType() : NOT_REMOTE_TYPE);
+      contentParent ? contentParent->GetRemoteType() : RemoteType::NotRemote());
   if (NS_WARN_IF(remoteType.isErr())) {
     ErrorPropagationOnMainThread(aBackgroundEventTarget, aActor,
                                  remoteType.unwrapErr());
diff --git a/gfx/ipc/GPUProcessHost.cpp b/gfx/ipc/GPUProcessHost.cpp
index e37ff4adb97b..e7f55a896c5e 100644
--- a/gfx/ipc/GPUProcessHost.cpp
+++ b/gfx/ipc/GPUProcessHost.cpp
@@ -60,7 +60,7 @@ bool GPUProcessHost::Launch(geckoargs::ChildProcessArgs aExtraOpts) {
 
   mPrefSerializer = MakeUnique<ipc::SharedPreferenceSerializer>();
   if (!mPrefSerializer->SerializeToSharedMemory(GeckoProcessType_GPU,
-                                                /* remoteType */ ""_ns)) {
+                                                /* remoteType */ {})) {
     return false;
   }
   mPrefSerializer->AddSharedPrefCmdLineArgs(*this, aExtraOpts);
diff --git a/gfx/ipc/GPUProcessManager.cpp b/gfx/ipc/GPUProcessManager.cpp
index 84f5323fe8ed..f47c3c2753f5 100644
--- a/gfx/ipc/GPUProcessManager.cpp
+++ b/gfx/ipc/GPUProcessManager.cpp
@@ -206,7 +206,7 @@ void GPUProcessManager::OnPreferenceChange(const char16_t* aData) {
                           /* isSanitized */ false, Nothing(), Nothing());
 
   Preferences::GetPreference(&pref, GeckoProcessType_GPU,
-                             /* remoteType */ ""_ns);
+                             /* remoteType */ {});
   if (mGPUChild) {
     MOZ_ASSERT(mQueuedPrefs.IsEmpty());
     mGPUChild->SendPreferenceUpdate(pref);
diff --git a/gfx/vr/ipc/VRProcessManager.cpp b/gfx/vr/ipc/VRProcessManager.cpp
index 7b1f5cb06c1d..a67ee5181de4 100644
--- a/gfx/vr/ipc/VRProcessManager.cpp
+++ b/gfx/vr/ipc/VRProcessManager.cpp
@@ -218,7 +218,7 @@ void VRProcessManager::OnPreferenceChange(const char16_t* aData) {
                           /* isSanitized */ false, Nothing(), Nothing());
 
   Preferences::GetPreference(&pref, GeckoProcessType_VR,
-                             /* remoteType */ ""_ns);
+                             /* remoteType */ {});
   if (!!mVRChild) {
     MOZ_ASSERT(mQueuedPrefs.IsEmpty());
     mVRChild->SendPreferenceUpdate(pref);
diff --git a/gfx/vr/ipc/VRProcessParent.cpp b/gfx/vr/ipc/VRProcessParent.cpp
index c8663fd09496..7d580506d783 100644
--- a/gfx/vr/ipc/VRProcessParent.cpp
+++ b/gfx/vr/ipc/VRProcessParent.cpp
@@ -52,7 +52,7 @@ bool VRProcessParent::Launch() {
 
   mPrefSerializer = MakeUnique<ipc::SharedPreferenceSerializer>();
   if (!mPrefSerializer->SerializeToSharedMemory(GeckoProcessType_VR,
-                                                /* remoteType */ ""_ns)) {
+                                                /* remoteType */ {})) {
     return false;
   }
   mPrefSerializer->AddSharedPrefCmdLineArgs(*this, extraArgs);
diff --git a/image/remote/RemoteImageProtocolHandler.cpp b/image/remote/RemoteImageProtocolHandler.cpp
index 388c3396d9ec..66f95691cf4a 100644
--- a/image/remote/RemoteImageProtocolHandler.cpp
+++ b/image/remote/RemoteImageProtocolHandler.cpp
@@ -57,7 +57,7 @@ static UniqueContentParentKeepAlive GetLaunchingContentParentForDecode(
   // We use the extension process as a fallback, because
   // it is usually running, and should be OK to parse images.
   return ContentParent::GetNewOrUsedLaunchingBrowserProcess(
-      EXTENSION_REMOTE_TYPE,
+      dom::RemoteType(dom::RemoteType::Kind::Extension),
       /* aGroup */ nullptr,
       /* aPriority */ hal::PROCESS_PRIORITY_FOREGROUND,
       /* aPreferUsed */ true);
diff --git a/ipc/glue/BackgroundImpl.cpp b/ipc/glue/BackgroundImpl.cpp
index e763b2f72913..b3c0f9b2296d 100644
--- a/ipc/glue/BackgroundImpl.cpp
+++ b/ipc/glue/BackgroundImpl.cpp
@@ -677,10 +677,12 @@ uint64_t BackgroundParent::GetChildID(PBackgroundParent* aBackgroundActor) {
 }
 
 // static
-nsCString BackgroundParent::GetRemoteType(PBackgroundParent* aBackgroundActor) {
+mozilla::dom::RemoteType BackgroundParent::GetRemoteType(
+    PBackgroundParent* aBackgroundActor) {
   ThreadsafeContentParentHandle* handle =
       GetContentParentHandle(aBackgroundActor);
-  return handle ? handle->GetRemoteType() : NOT_REMOTE_TYPE;
+  return handle ? handle->GetRemoteType()
+                : mozilla::dom::RemoteType::NotRemote();
 }
 
 // static
diff --git a/ipc/glue/BackgroundParent.h b/ipc/glue/BackgroundParent.h
index 286f7c081741..278dbd9c0f9f 100644
--- a/ipc/glue/BackgroundParent.h
+++ b/ipc/glue/BackgroundParent.h
@@ -87,7 +87,8 @@ class BackgroundParent final {
 
   static uint64_t GetChildID(PBackgroundParent* aBackgroundActor);
 
-  static nsCString GetRemoteType(PBackgroundParent* aBackgroundActor);
+  static mozilla::dom::RemoteType GetRemoteType(
+      PBackgroundParent* aBackgroundActor);
 
   // Whenever receiving a Principal we need to validate that Principal case
   // by case. The options can customize the behaviour of the checks.
diff --git a/ipc/glue/BackgroundParentImpl.cpp b/ipc/glue/BackgroundParentImpl.cpp
index 4ad06e1ac4a1..baeb634e9f5e 100644
--- a/ipc/glue/BackgroundParentImpl.cpp
+++ b/ipc/glue/BackgroundParentImpl.cpp
@@ -487,7 +487,7 @@ mozilla::ipc::IPCResult BackgroundParentImpl::RecvCreateFileSystemManagerParent(
   // The inference process uses ChromeWorkers which have a system principal,
   // so system principals must be allowed there.
   EnumSet<dom::ValidatePrincipalOptions> options;
-  if (BackgroundParent::GetRemoteType(this) == INFERENCE_REMOTE_TYPE) {
+  if (BackgroundParent::GetRemoteType(this).IsInference()) {
     options += dom::ValidatePrincipalOptions::AllowSystemIfLoaded;
   }
   if (!BackgroundParent::ValidatePrincipalInfo(this, aPrincipalInfo, options)) {
@@ -660,7 +660,7 @@ mozilla::ipc::IPCResult BackgroundParentImpl::RecvPFileCreatorConstructor(
   if (!parent) {
     isFileRemoteType = true;
   } else {
-    isFileRemoteType = parent->GetRemoteType() == FILE_REMOTE_TYPE;
+    isFileRemoteType = parent->GetRemoteType().IsFile();
   }
 
   dom::FileCreatorParent* actor =
diff --git a/ipc/glue/BackgroundUtils.cpp b/ipc/glue/BackgroundUtils.cpp
index f33564f23062..2251dad0e111 100644
--- a/ipc/glue/BackgroundUtils.cpp
+++ b/ipc/glue/BackgroundUtils.cpp
@@ -439,7 +439,7 @@ nsresult LoadInfoToLoadInfoArgs(nsILoadInfo* aLoadInfo,
     SerializeURI(resultPrincipalURI, optionalResultPrincipalURI);
   }
 
-  nsCString triggeringRemoteType;
+  RemoteType triggeringRemoteType;
   rv = aLoadInfo->GetTriggeringRemoteType(triggeringRemoteType);
   NS_ENSURE_SUCCESS(rv, rv);
 
@@ -618,13 +618,13 @@ nsresult LoadInfoToLoadInfoArgs(nsILoadInfo* aLoadInfo,
 }
 
 nsresult LoadInfoArgsToLoadInfo(const LoadInfoArgs& aLoadInfoArgs,
-                                const nsACString& aOriginRemoteType,
+                                const RemoteType& aOriginRemoteType,
                                 nsILoadInfo** outLoadInfo) {
   return LoadInfoArgsToLoadInfo(aLoadInfoArgs, aOriginRemoteType, nullptr,
                                 outLoadInfo);
 }
 nsresult LoadInfoArgsToLoadInfo(const LoadInfoArgs& aLoadInfoArgs,
-                                const nsACString& aOriginRemoteType,
+                                const RemoteType& aOriginRemoteType,
                                 nsINode* aCspToInheritLoadingContext,
                                 nsILoadInfo** outLoadInfo) {
   RefPtr<LoadInfo> loadInfo;
@@ -638,13 +638,13 @@ nsresult LoadInfoArgsToLoadInfo(const LoadInfoArgs& aLoadInfoArgs,
 }
 
 nsresult LoadInfoArgsToLoadInfo(const LoadInfoArgs& aLoadInfoArgs,
-                                const nsACString& aOriginRemoteType,
+                                const RemoteType& aOriginRemoteType,
                                 LoadInfo** outLoadInfo) {
   return LoadInfoArgsToLoadInfo(aLoadInfoArgs, aOriginRemoteType, nullptr,
                                 outLoadInfo);
 }
 nsresult LoadInfoArgsToLoadInfo(const LoadInfoArgs& loadInfoArgs,
-                                const nsACString& aOriginRemoteType,
+                                const RemoteType& aOriginRemoteType,
                                 nsINode* aCspToInheritLoadingContext,
                                 LoadInfo** outLoadInfo) {
   nsCOMPtr<nsIPrincipal> loadingPrincipal;
@@ -725,8 +725,8 @@ nsresult LoadInfoArgsToLoadInfo(const LoadInfoArgs& loadInfoArgs,
   // This means that the triggering remote type will be reset if a LoadInfo is
   // bounced through a content process, as the LoadInfo can no longer be
   // validated to be coming from the originally specified remote type.
-  nsCString triggeringRemoteType = loadInfoArgs.triggeringRemoteType();
-  if (aOriginRemoteType != NOT_REMOTE_TYPE &&
+  RemoteType triggeringRemoteType = loadInfoArgs.triggeringRemoteType();
+  if (!aOriginRemoteType.IsNotRemote() &&
       aOriginRemoteType != triggeringRemoteType) {
     triggeringRemoteType = aOriginRemoteType;
   }
diff --git a/ipc/glue/BackgroundUtils.h b/ipc/glue/BackgroundUtils.h
index 02c4d8291612..50559ba1d10f 100644
--- a/ipc/glue/BackgroundUtils.h
+++ b/ipc/glue/BackgroundUtils.h
@@ -138,20 +138,22 @@ nsresult LoadInfoToLoadInfoArgs(nsILoadInfo* aLoadInfo,
 /**
  * Convert LoadInfoArgs to a LoadInfo.
  */
-nsresult LoadInfoArgsToLoadInfo(const mozilla::net::LoadInfoArgs& aLoadInfoArgs,
-                                const nsACString& aOriginRemoteType,
-                                nsILoadInfo** outLoadInfo);
-nsresult LoadInfoArgsToLoadInfo(const mozilla::net::LoadInfoArgs& aLoadInfoArgs,
-                                const nsACString& aOriginRemoteType,
-                                nsINode* aCspToInheritLoadingContext,
-                                nsILoadInfo** outLoadInfo);
-nsresult LoadInfoArgsToLoadInfo(const net::LoadInfoArgs& aLoadInfoArgs,
-                                const nsACString& aOriginRemoteType,
-                                mozilla::net::LoadInfo** outLoadInfo);
-nsresult LoadInfoArgsToLoadInfo(const net::LoadInfoArgs& aLoadInfoArgs,
-                                const nsACString& aOriginRemoteType,
-                                nsINode* aCspToInheritLoadingContext,
-                                mozilla::net::LoadInfo** outLoadInfo);
+nsresult LoadInfoArgsToLoadInfo(
+    const mozilla::net::LoadInfoArgs& aLoadInfoArgs,
+    const mozilla::dom::RemoteType& aOriginRemoteType,
+    nsILoadInfo** outLoadInfo);
+nsresult LoadInfoArgsToLoadInfo(
+    const mozilla::net::LoadInfoArgs& aLoadInfoArgs,
+    const mozilla::dom::RemoteType& aOriginRemoteType,
+    nsINode* aCspToInheritLoadingContext, nsILoadInfo** outLoadInfo);
+nsresult LoadInfoArgsToLoadInfo(
+    const net::LoadInfoArgs& aLoadInfoArgs,
+    const mozilla::dom::RemoteType& aOriginRemoteType,
+    mozilla::net::LoadInfo** outLoadInfo);
+nsresult LoadInfoArgsToLoadInfo(
+    const net::LoadInfoArgs& aLoadInfoArgs,
+    const mozilla::dom::RemoteType& aOriginRemoteType,
+    nsINode* aCspToInheritLoadingContext, mozilla::net::LoadInfo** outLoadInfo);
 
 /**
  * Fills ParentLoadInfoForwarderArgs with properties we want to carry to child
diff --git a/ipc/glue/ProcessUtils.h b/ipc/glue/ProcessUtils.h
index 6eca8be3faeb..fe2a08547114 100644
--- a/ipc/glue/ProcessUtils.h
+++ b/ipc/glue/ProcessUtils.h
@@ -6,6 +6,7 @@
 #define mozilla_ipc_ProcessUtils_h
 
 #include "mozilla/GeckoArgs.h"
+#include "mozilla/dom/RemoteType.h"
 #include "mozilla/ipc/FileDescriptor.h"
 #include "mozilla/ipc/SharedMemoryHandle.h"
 #include "mozilla/ipc/SharedMemoryMapping.h"
@@ -27,8 +28,9 @@ class SharedPreferenceSerializer final {
   SharedPreferenceSerializer(SharedPreferenceSerializer&& aOther);
   ~SharedPreferenceSerializer();
 
-  bool SerializeToSharedMemory(const GeckoProcessType aDestinationProcessType,
-                               const nsACString& aDestinationRemoteType);
+  bool SerializeToSharedMemory(
+      const GeckoProcessType aDestinationProcessType,
+      const mozilla::dom::RemoteType& aDestinationRemoteType);
 
   const ReadOnlySharedMemoryHandle& GetPrefsHandle() const {
     return mPrefsHandle;
diff --git a/ipc/glue/ProcessUtils_common.cpp b/ipc/glue/ProcessUtils_common.cpp
index e7f52a8d742b..1a87ab12dbf2 100644
--- a/ipc/glue/ProcessUtils_common.cpp
+++ b/ipc/glue/ProcessUtils_common.cpp
@@ -32,13 +32,12 @@ SharedPreferenceSerializer::SharedPreferenceSerializer(
 
 bool SharedPreferenceSerializer::SerializeToSharedMemory(
     const GeckoProcessType aDestinationProcessType,
-    const nsACString& aDestinationRemoteType) {
+    const mozilla::dom::RemoteType& aDestinationRemoteType) {
   mPrefMapHandle = Preferences::EnsureSnapshot();
 
   bool destIsWebContent =
       aDestinationProcessType == GeckoProcessType_Content &&
-      (StringBeginsWith(aDestinationRemoteType, WEB_REMOTE_TYPE) ||
-       StringBeginsWith(aDestinationRemoteType, PREALLOC_REMOTE_TYPE));
+      (aDestinationRemoteType.IsWeb() || aDestinationRemoteType.IsPrealloc());
 
   // Serialize the early prefs.
   nsAutoCStringN<1024> prefs;
diff --git a/ipc/glue/UtilityProcessHost.cpp b/ipc/glue/UtilityProcessHost.cpp
index 16386a9fb5d8..f4b340a832de 100644
--- a/ipc/glue/UtilityProcessHost.cpp
+++ b/ipc/glue/UtilityProcessHost.cpp
@@ -92,7 +92,7 @@ bool UtilityProcessHost::Launch(geckoargs::ChildProcessArgs aExtraOpts) {
 
   mPrefSerializer = MakeUnique<ipc::SharedPreferenceSerializer>();
   if (!mPrefSerializer->SerializeToSharedMemory(GeckoProcessType_Utility,
-                                                /* remoteType */ ""_ns)) {
+                                                /* remoteType */ {})) {
     return false;
   }
   mPrefSerializer->AddSharedPrefCmdLineArgs(*this, aExtraOpts);
diff --git a/ipc/glue/UtilityProcessManager.cpp b/ipc/glue/UtilityProcessManager.cpp
index fc608e33dc96..e80799adc1ca 100644
--- a/ipc/glue/UtilityProcessManager.cpp
+++ b/ipc/glue/UtilityProcessManager.cpp
@@ -122,7 +122,7 @@ void UtilityProcessManager::OnPreferenceChange(const char16_t* aData) {
   mozilla::dom::Pref pref(strData, /* isLocked */ false,
                           /* isSanitized */ false, Nothing(), Nothing());
   Preferences::GetPreference(&pref, GeckoProcessType_Utility,
-                             /* remoteType */ ""_ns);
+                             /* remoteType */ {});
 
   for (auto& p : mProcesses) {
     if (!p) {
diff --git a/ipc/ipdl/test/gtest/IPDLUnitTest.cpp b/ipc/ipdl/test/gtest/IPDLUnitTest.cpp
index 7f50215cc13a..8de1e8a28ae9 100644
--- a/ipc/ipdl/test/gtest/IPDLUnitTest.cpp
+++ b/ipc/ipdl/test/gtest/IPDLUnitTest.cpp
@@ -46,7 +46,7 @@ already_AddRefed<IPDLUnitTestParent> IPDLUnitTestParent::CreateCrossProcess() {
 
   auto prefSerializer = MakeUnique<ipc::SharedPreferenceSerializer>();
   if (!prefSerializer->SerializeToSharedMemory(GeckoProcessType_IPDLUnitTest,
-                                               /* remoteType */ ""_ns)) {
+                                               /* remoteType */ {})) {
     ADD_FAILURE()
         << "SharedPreferenceSerializer::SerializeToSharedMemory failed";
     return nullptr;
diff --git a/js/xpconnect/loader/ScriptPreloader.cpp b/js/xpconnect/loader/ScriptPreloader.cpp
index 8aec5b88c7f3..1c779e72d157 100644
--- a/js/xpconnect/loader/ScriptPreloader.cpp
+++ b/js/xpconnect/loader/ScriptPreloader.cpp
@@ -235,11 +235,12 @@ void ScriptPreloader::InitContentChild(ContentParent& parent) {
   }
 }
 
-ProcessType ScriptPreloader::GetChildProcessType(const nsACString& remoteType) {
-  if (remoteType == EXTENSION_REMOTE_TYPE) {
+ProcessType ScriptPreloader::GetChildProcessType(
+    const dom::RemoteType& remoteType) {
+  if (remoteType.IsExtension()) {
     return ProcessType::Extension;
   }
-  if (remoteType == PRIVILEGEDABOUT_REMOTE_TYPE) {
+  if (remoteType.IsPrivilegedAbout()) {
     return ProcessType::PrivilegedAbout;
   }
   return ProcessType::Web;
diff --git a/js/xpconnect/loader/ScriptPreloader.h b/js/xpconnect/loader/ScriptPreloader.h
index 034666277f23..c9da15647761 100644
--- a/js/xpconnect/loader/ScriptPreloader.h
+++ b/js/xpconnect/loader/ScriptPreloader.h
@@ -42,7 +42,8 @@
 namespace mozilla {
 namespace dom {
 class ContentParent;
-}
+struct RemoteType;
+}  // namespace dom
 namespace ipc {
 class FileDescriptor;
 }
@@ -98,7 +99,7 @@ class ScriptPreloader : public nsIObserver,
   static void DeleteSingleton();
   static void DeleteCacheDataSingleton();
 
-  static ProcessType GetChildProcessType(const nsACString& remoteType);
+  static ProcessType GetChildProcessType(const dom::RemoteType& remoteType);
 
   // Fill some options that should be consistent across all scripts stored
   // into preloader cache.
diff --git a/layout/base/PresShell.cpp b/layout/base/PresShell.cpp
index f78806ec1f88..7d800a57e6f3 100644
--- a/layout/base/PresShell.cpp
+++ b/layout/base/PresShell.cpp
@@ -1069,7 +1069,7 @@ void PresShell::Destroy() {
       return false;
     }
     if (XRE_IsContentProcess() &&
-        IsExtensionRemoteType(ContentChild::GetSingleton()->GetRemoteType())) {
+        ContentChild::GetSingleton()->GetRemoteType().IsExtension()) {
       // Also omit presShells from the extension process because they sometimes
       // can't be zoomed by the user.
       return false;
diff --git a/mobile/android/components/geckoview/GeckoViewContentChannelParent.cpp b/mobile/android/components/geckoview/GeckoViewContentChannelParent.cpp
index b6a30d4f3c23..dff674ded417 100644
--- a/mobile/android/components/geckoview/GeckoViewContentChannelParent.cpp
+++ b/mobile/android/components/geckoview/GeckoViewContentChannelParent.cpp
@@ -60,7 +60,7 @@ GeckoViewContentChannelParent::Delete() {
 }
 
 NS_IMETHODIMP
-GeckoViewContentChannelParent::GetRemoteType(nsACString& aRemoteType) {
+GeckoViewContentChannelParent::GetRemoteType(dom::RemoteType& aRemoteType) {
   if (!CanSend()) {
     return NS_ERROR_UNEXPECTED;
   }
@@ -164,7 +164,7 @@ bool GeckoViewContentChannelParent::Init(
     return false;
   }
 
-  nsAutoCString remoteType;
+  dom::RemoteType remoteType;
   rv = GetRemoteType(remoteType);
   if (MOZ_UNLIKELY(NS_FAILED(rv))) {
     return false;
diff --git a/modules/libpref/Preferences.cpp b/modules/libpref/Preferences.cpp
index 09c9ef5f008d..cf7596ff78c4 100644
--- a/modules/libpref/Preferences.cpp
+++ b/modules/libpref/Preferences.cpp
@@ -5257,13 +5257,12 @@ void Preferences::SetPreference(const dom::Pref& aDomPref) {
 /* static */
 void Preferences::GetPreference(dom::Pref* aDomPref,
                                 const GeckoProcessType aDestinationProcessType,
-                                const nsACString& aDestinationRemoteType) {
+                                const dom::RemoteType& aDestinationRemoteType) {
   MOZ_ASSERT(XRE_IsParentProcess());
   bool destIsWebContent =
       aDestinationProcessType == GeckoProcessType_Content &&
-      (StringBeginsWith(aDestinationRemoteType, WEB_REMOTE_TYPE) ||
-       StringBeginsWith(aDestinationRemoteType, PREALLOC_REMOTE_TYPE) ||
-       StringBeginsWith(aDestinationRemoteType, PRIVILEGEDMOZILLA_REMOTE_TYPE));
+      (aDestinationRemoteType.IsWeb() || aDestinationRemoteType.IsPrealloc() ||
+       aDestinationRemoteType.IsPrivilegedMozilla());
 
   Pref* pref = pref_HashTableLookup(aDomPref->name().get());
   if (pref && pref->HasAdvisablySizedValues()) {
diff --git a/modules/libpref/Preferences.h b/modules/libpref/Preferences.h
index bb0f9494a5f1..188bea22c42f 100644
--- a/modules/libpref/Preferences.h
+++ b/modules/libpref/Preferences.h
@@ -15,6 +15,7 @@
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/MozPromise.h"
 #include "mozilla/StaticPtr.h"
+#include "mozilla/dom/RemoteType.h"
 #include "mozilla/ipc/SharedMemoryHandle.h"
 #include "nsCOMPtr.h"
 #include "nsIObserver.h"
@@ -436,7 +437,7 @@ class Preferences final : public nsIPrefService,
   // used to pass the update to content processes.
   static void GetPreference(dom::Pref* aPref,
                             const GeckoProcessType aDestinationProcessType,
-                            const nsACString& aDestinationRemoteType);
+                            const dom::RemoteType& aDestinationRemoteType);
   static void SetPreference(const dom::Pref& aPref);
 
 #ifdef DEBUG
diff --git a/netwerk/base/LoadInfo.cpp b/netwerk/base/LoadInfo.cpp
index 18d89d2e1dc3..8296f069eac2 100644
--- a/netwerk/base/LoadInfo.cpp
+++ b/netwerk/base/LoadInfo.cpp
@@ -57,12 +57,12 @@ using namespace mozilla::dom;
 
 namespace mozilla::net {
 
-static nsCString CurrentRemoteType() {
+static const RemoteType& CurrentRemoteType() {
   MOZ_ASSERT(XRE_IsParentProcess() || XRE_IsContentProcess());
   if (ContentChild* cc = ContentChild::GetSingleton()) {
-    return nsCString(cc->GetRemoteType());
+    return cc->GetRemoteType();
   }
-  return NOT_REMOTE_TYPE;
+  return RemoteType::NotRemote();
 }
 
 static nsContentPolicyType InternalContentPolicyTypeForFrame(
@@ -141,7 +141,7 @@ bool LoadInfo::IsDocumentMissingClientInfo() {
 
 /* static */ already_AddRefed<LoadInfo> LoadInfo::CreateForDocument(
     dom::CanonicalBrowsingContext* aBrowsingContext, nsIURI* aURI,
-    nsIPrincipal* aTriggeringPrincipal, const nsACString& aTriggeringRemoteType,
+    nsIPrincipal* aTriggeringPrincipal, const RemoteType& aTriggeringRemoteType,
     const OriginAttributes& aOriginAttributes, nsSecurityFlags aSecurityFlags,
     uint32_t aSandboxFlags) {
   return MakeAndAddRef<LoadInfo>(aBrowsingContext, aURI, aTriggeringPrincipal,
@@ -151,7 +151,7 @@ bool LoadInfo::IsDocumentMissingClientInfo() {
 
 /* static */ already_AddRefed<LoadInfo> LoadInfo::CreateForFrame(
     dom::CanonicalBrowsingContext* aBrowsingContext,
-    nsIPrincipal* aTriggeringPrincipal, const nsACString& aTriggeringRemoteType,
+    nsIPrincipal* aTriggeringPrincipal, const RemoteType& aTriggeringRemoteType,
     nsSecurityFlags aSecurityFlags, uint32_t aSandboxFlags) {
   return MakeAndAddRef<LoadInfo>(aBrowsingContext, aTriggeringPrincipal,
                                  aTriggeringRemoteType, aSecurityFlags,
@@ -469,7 +469,7 @@ LoadInfo::LoadInfo(nsPIDOMWindowOuter* aOuterWindow, nsIURI* aURI,
 
 LoadInfo::LoadInfo(dom::CanonicalBrowsingContext* aBrowsingContext,
                    nsIURI* aURI, nsIPrincipal* aTriggeringPrincipal,
-                   const nsACString& aTriggeringRemoteType,
+                   const RemoteType& aTriggeringRemoteType,
                    const OriginAttributes& aOriginAttributes,
                    nsSecurityFlags aSecurityFlags, uint32_t aSandboxFlags)
     : mTriggeringPrincipal(aTriggeringPrincipal),
@@ -564,7 +564,7 @@ LoadInfo::LoadInfo(dom::CanonicalBrowsingContext* aBrowsingContext,
 
 LoadInfo::LoadInfo(dom::WindowGlobalParent* aParentWGP,
                    nsIPrincipal* aTriggeringPrincipal,
-                   const nsACString& aTriggeringRemoteType,
+                   const RemoteType& aTriggeringRemoteType,
                    nsContentPolicyType aContentPolicyType,
                    nsSecurityFlags aSecurityFlags, uint32_t aSandboxFlags)
     : mTriggeringPrincipal(aTriggeringPrincipal),
@@ -693,7 +693,7 @@ LoadInfo::LoadInfo(dom::WindowGlobalParent* aParentWGP,
 // Used for TYPE_FRAME or TYPE_IFRAME load.
 LoadInfo::LoadInfo(dom::CanonicalBrowsingContext* aBrowsingContext,
                    nsIPrincipal* aTriggeringPrincipal,
-                   const nsACString& aTriggeringRemoteType,
+                   const RemoteType& aTriggeringRemoteType,
                    nsSecurityFlags aSecurityFlags, uint32_t aSandboxFlags)
     : LoadInfo(aBrowsingContext->GetParentWindowContext(), aTriggeringPrincipal,
                aTriggeringRemoteType,
@@ -763,7 +763,7 @@ LoadInfo::LoadInfo(
     nsIURI* aResultPrincipalURI, nsICookieJarSettings* aCookieJarSettings,
     nsIPolicyContainer* aPolicyContainerToInherit,
     const Maybe<dom::FeaturePolicyInfo>& aContainerFeaturePolicyInfo,
-    const nsACString& aTriggeringRemoteType,
+    const RemoteType& aTriggeringRemoteType,
     const nsID& aSandboxedNullPrincipalID, const Maybe<ClientInfo>& aClientInfo,
     const Maybe<ClientInfo>& aReservedClientInfo,
     const Maybe<ClientInfo>& aInitialClientInfo,
@@ -986,13 +986,19 @@ void LoadInfo::ResetSandboxedNullPrincipalID() {
 nsIPrincipal* LoadInfo::GetTopLevelPrincipal() { return mTopLevelPrincipal; }
 
 NS_IMETHODIMP
-LoadInfo::GetTriggeringRemoteType(nsACString& aTriggeringRemoteType) {
+LoadInfo::GetXPCOMTriggeringRemoteType(nsACString& aTriggeringRemoteType) {
+  aTriggeringRemoteType = mTriggeringRemoteType.Stringify();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+LoadInfo::GetTriggeringRemoteType(RemoteType& aTriggeringRemoteType) {
   aTriggeringRemoteType = mTriggeringRemoteType;
   return NS_OK;
 }
 
 NS_IMETHODIMP
-LoadInfo::SetTriggeringRemoteType(const nsACString& aTriggeringRemoteType) {
+LoadInfo::SetTriggeringRemoteType(const RemoteType& aTriggeringRemoteType) {
   mTriggeringRemoteType = aTriggeringRemoteType;
   return NS_OK;
 }
diff --git a/netwerk/base/LoadInfo.h b/netwerk/base/LoadInfo.h
index 9e48f631d80c..7d4eb0f8ef0c 100644
--- a/netwerk/base/LoadInfo.h
+++ b/netwerk/base/LoadInfo.h
@@ -46,7 +46,7 @@ class WebTransportSessionProxy;
 namespace ipc {
 // we have to forward declare that function so we can use it as a friend.
 nsresult LoadInfoArgsToLoadInfo(const mozilla::net::LoadInfoArgs& aLoadInfoArgs,
-                                const nsACString& aOriginRemoteType,
+                                const dom::RemoteType& aOriginRemoteType,
                                 nsINode* aCspToInheritLoadingContext,
                                 net::LoadInfo** outLoadInfo);
 
@@ -255,7 +255,7 @@ class LoadInfo final : public nsILoadInfo {
   static already_AddRefed<LoadInfo> CreateForDocument(
       dom::CanonicalBrowsingContext* aBrowsingContext, nsIURI* aURI,
       nsIPrincipal* aTriggeringPrincipal,
-      const nsACString& aTriggeringRemoteType,
+      const dom::RemoteType& aTriggeringRemoteType,
       const OriginAttributes& aOriginAttributes, nsSecurityFlags aSecurityFlags,
       uint32_t aSandboxFlags);
 
@@ -263,8 +263,8 @@ class LoadInfo final : public nsILoadInfo {
   static already_AddRefed<LoadInfo> CreateForFrame(
       dom::CanonicalBrowsingContext* aBrowsingContext,
       nsIPrincipal* aTriggeringPrincipal,
-      const nsACString& aTriggeringRemoteType, nsSecurityFlags aSecurityFlags,
-      uint32_t aSandboxFlags);
+      const dom::RemoteType& aTriggeringRemoteType,
+      nsSecurityFlags aSecurityFlags, uint32_t aSandboxFlags);
 
   // Use for non-{TYPE_DOCUMENT|TYPE_FRAME|TYPE_IFRAME} load.
   static already_AddRefed<LoadInfo> CreateForNonDocument(
@@ -294,7 +294,7 @@ class LoadInfo final : public nsILoadInfo {
   // Used for TYPE_DOCUMENT load.
   LoadInfo(dom::CanonicalBrowsingContext* aBrowsingContext, nsIURI* aURI,
            nsIPrincipal* aTriggeringPrincipal,
-           const nsACString& aTriggeringRemoteType,
+           const dom::RemoteType& aTriggeringRemoteType,
            const OriginAttributes& aOriginAttributes,
            nsSecurityFlags aSecurityFlags, uint32_t aSandboxFlags);
 
@@ -302,14 +302,14 @@ class LoadInfo final : public nsILoadInfo {
   // Used for TYPE_FRAME or TYPE_IFRAME load.
   LoadInfo(dom::CanonicalBrowsingContext* aBrowsingContext,
            nsIPrincipal* aTriggeringPrincipal,
-           const nsACString& aTriggeringRemoteType,
+           const dom::RemoteType& aTriggeringRemoteType,
            nsSecurityFlags aSecurityFlags, uint32_t aSandboxFlags);
 
   // Used for loads initiated by DocumentLoadListener that are not
   // TYPE_DOCUMENT | TYPE_FRAME | TYPE_FRAME.
   LoadInfo(dom::WindowGlobalParent* aParentWGP,
            nsIPrincipal* aTriggeringPrincipal,
-           const nsACString& aTriggeringRemoteType,
+           const dom::RemoteType& aTriggeringRemoteType,
            nsContentPolicyType aContentPolicyType,
            nsSecurityFlags aSecurityFlags, uint32_t aSandboxFlags);
 
@@ -404,7 +404,7 @@ class LoadInfo final : public nsILoadInfo {
            nsICookieJarSettings* aCookieJarSettings,
            nsIPolicyContainer* aPolicyContainerToInherit,
            const Maybe<dom::FeaturePolicyInfo>& aContainerFeaturePolicyInfo,
-           const nsACString& aTriggeringRemoteType,
+           const dom::RemoteType& aTriggeringRemoteType,
            const nsID& aSandboxedNullPrincipalID,
            const Maybe<mozilla::dom::ClientInfo>& aClientInfo,
            const Maybe<mozilla::dom::ClientInfo>& aReservedClientInfo,
@@ -443,8 +443,8 @@ class LoadInfo final : public nsILoadInfo {
 
   friend nsresult mozilla::ipc::LoadInfoArgsToLoadInfo(
       const mozilla::net::LoadInfoArgs& aLoadInfoArgs,
-      const nsACString& aOriginRemoteType, nsINode* aCspToInheritLoadingContext,
-      net::LoadInfo** outLoadInfo);
+      const dom::RemoteType& aOriginRemoteType,
+      nsINode* aCspToInheritLoadingContext, net::LoadInfo** outLoadInfo);
 
   ~LoadInfo();
 
@@ -488,7 +488,7 @@ class LoadInfo final : public nsILoadInfo {
   nsCOMPtr<nsICookieJarSettings> mCookieJarSettings;
   nsCOMPtr<nsIPolicyContainer> mPolicyContainerToInherit;
   Maybe<dom::FeaturePolicyInfo> mContainerFeaturePolicyInfo;
-  nsCString mTriggeringRemoteType;
+  dom::RemoteType mTriggeringRemoteType;
   nsID mSandboxedNullPrincipalID;
 
   Maybe<mozilla::dom::ClientInfo> mClientInfo;
diff --git a/netwerk/base/TRRLoadInfo.cpp b/netwerk/base/TRRLoadInfo.cpp
index 9a4cf0648708..312dc82bc385 100644
--- a/netwerk/base/TRRLoadInfo.cpp
+++ b/netwerk/base/TRRLoadInfo.cpp
@@ -85,12 +85,17 @@ void TRRLoadInfo::ResetSandboxedNullPrincipalID() {}
 nsIPrincipal* TRRLoadInfo::GetTopLevelPrincipal() { return nullptr; }
 
 NS_IMETHODIMP
-TRRLoadInfo::GetTriggeringRemoteType(nsACString& aTriggeringRemoteType) {
+TRRLoadInfo::GetXPCOMTriggeringRemoteType(nsACString& aTriggeringRemoteType) {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
 NS_IMETHODIMP
-TRRLoadInfo::SetTriggeringRemoteType(const nsACString& aTriggeringRemoteType) {
+TRRLoadInfo::GetTriggeringRemoteType(RemoteType& aTriggeringRemoteType) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+TRRLoadInfo::SetTriggeringRemoteType(const RemoteType& aTriggeringRemoteType) {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
diff --git a/netwerk/base/nsBaseParentChannel.cpp b/netwerk/base/nsBaseParentChannel.cpp
index cf51fbe2ee2b..ba7767aab901 100644
--- a/netwerk/base/nsBaseParentChannel.cpp
+++ b/netwerk/base/nsBaseParentChannel.cpp
@@ -43,8 +43,8 @@ nsBaseParentChannel::Delete() {
 }
 
 NS_IMETHODIMP
-nsBaseParentChannel::GetRemoteType(nsACString& aRemoteType) {
-  aRemoteType = mRemoteType;
+nsBaseParentChannel::GetRemoteType(mozilla::dom::RemoteType& _retval) {
+  _retval = mRemoteType;
   return NS_OK;
 }
 
diff --git a/netwerk/base/nsBaseParentChannel.h b/netwerk/base/nsBaseParentChannel.h
index 4268c7465b7f..2cf0179559cb 100644
--- a/netwerk/base/nsBaseParentChannel.h
+++ b/netwerk/base/nsBaseParentChannel.h
@@ -5,6 +5,7 @@
 #ifndef nsBaseParentChannel_h
 #define nsBaseParentChannel_h
 
+#include "mozilla/dom/RemoteType.h"
 #include "nsIParentChannel.h"
 
 // Basic type which implements a no-op nsIParentChannel instance.
@@ -24,13 +25,13 @@ class nsBaseParentChannel : public nsIParentChannel {
   NS_DECL_NSIREQUESTOBSERVER
   NS_DECL_NSISTREAMLISTENER
 
-  explicit nsBaseParentChannel(const nsACString& aRemoteType)
+  explicit nsBaseParentChannel(const mozilla::dom::RemoteType& aRemoteType)
       : mRemoteType(aRemoteType) {}
 
  protected:
   virtual ~nsBaseParentChannel() = default;
 
-  nsCString mRemoteType;
+  mozilla::dom::RemoteType mRemoteType;
 };
 
 #endif  // nsBaseParentChannel_h
diff --git a/netwerk/base/nsILoadInfo.idl b/netwerk/base/nsILoadInfo.idl
index 5529ed0ea4c2..0cde3cee553a 100644
--- a/netwerk/base/nsILoadInfo.idl
+++ b/netwerk/base/nsILoadInfo.idl
@@ -34,6 +34,7 @@ class ClientInfo;
 class ClientSource;
 struct FeaturePolicyInfo;
 class PerformanceStorage;
+struct RemoteType;
 class ServiceWorkerDescriptor;
 enum class RequestMode : uint8_t;
 enum class ForceMediaDocument : uint8_t;
@@ -64,6 +65,8 @@ native OriginAttributes(mozilla::OriginAttributes);
 [ref] native const_FeaturePolicyInfoRef(const mozilla::dom::FeaturePolicyInfo);
       native MaybeRequestMode(mozilla::Maybe<mozilla::dom::RequestMode>);
       native ForceMediaDocument(mozilla::dom::ForceMediaDocument);
+[ref] native RemoteType(mozilla::dom::RemoteType);
+[ref] native const_RemoteTypeRef(const mozilla::dom::RemoteType);
 
 typedef unsigned long nsSecurityFlags;
 
@@ -339,7 +342,11 @@ interface nsILoadInfo : nsISupports
    * reset to the remote type of the sending process when sent from a content
    * process to the parent process.
    */
-  attribute AUTF8String triggeringRemoteType;
+  [binaryname(XPCOMTriggeringRemoteType)]
+  readonly attribute AUTF8String triggeringRemoteType;
+
+  [noscript] RemoteType getTriggeringRemoteType();
+  [noscript] void setTriggeringRemoteType(in const_RemoteTypeRef aTriggeringRemoteType);
 
   /**
    * For non-document loads the principalToInherit is always null. For
diff --git a/netwerk/base/nsIOService.cpp b/netwerk/base/nsIOService.cpp
index 2dd436d71707..73066c2678e0 100644
--- a/netwerk/base/nsIOService.cpp
+++ b/netwerk/base/nsIOService.cpp
@@ -715,7 +715,7 @@ void nsIOService::NotifySocketProcessPrefsChanged(const char* aName) {
                  /* isSanitized */ false, Nothing(), Nothing());
 
   Preferences::GetPreference(&pref, GeckoProcessType_Socket,
-                             /* remoteType */ ""_ns);
+                             /* remoteType */ {});
   auto sendPrefUpdate = [pref = std::move(pref)]() mutable {
     (void)gIOService->mSocketProcess->GetActor()->SendPreferenceUpdate(
         std::move(pref));
diff --git a/netwerk/base/nsIParentChannel.idl b/netwerk/base/nsIParentChannel.idl
index 92af6004934a..e6874ee8f8bc 100644
--- a/netwerk/base/nsIParentChannel.idl
+++ b/netwerk/base/nsIParentChannel.idl
@@ -9,6 +9,9 @@ interface nsIRemoteTab;
 
 %{C++
 namespace mozilla {
+namespace dom {
+struct RemoteType;
+}
 namespace net {
 class ParentChannelListener;
 }
@@ -16,6 +19,7 @@ class ParentChannelListener;
 %}
 
 [ptr] native ParentChannelListener(mozilla::net::ParentChannelListener);
+[ref] native RemoteType(mozilla::dom::RemoteType);
 
 /**
  * Implemented by chrome side of IPC protocols.
@@ -72,5 +76,5 @@ interface nsIParentChannel : nsIStreamListener
   /**
    * The remote type of the target process for this load.
    */
-  readonly attribute AUTF8String remoteType;
+  [noscript] RemoteType getRemoteType();
 };
diff --git a/netwerk/ipc/DocumentChannelChild.cpp b/netwerk/ipc/DocumentChannelChild.cpp
index 11747201b980..2a85d78c8123 100644
--- a/netwerk/ipc/DocumentChannelChild.cpp
+++ b/netwerk/ipc/DocumentChannelChild.cpp
@@ -243,9 +243,9 @@ IPCResult DocumentChannelChild::RecvRedirectToRealChannel(
     cspToInheritLoadingDocument = do_QueryReferent(ctx);
   }
   nsCOMPtr<nsILoadInfo> loadInfo;
-  MOZ_ALWAYS_SUCCEEDS(LoadInfoArgsToLoadInfo(aArgs.loadInfo(), NOT_REMOTE_TYPE,
-                                             cspToInheritLoadingDocument,
-                                             getter_AddRefs(loadInfo)));
+  MOZ_ALWAYS_SUCCEEDS(LoadInfoArgsToLoadInfo(
+      aArgs.loadInfo(), RemoteType::NotRemote(), cspToInheritLoadingDocument,
+      getter_AddRefs(loadInfo)));
 
   mRedirectResolver = std::move(aResolve);
 
diff --git a/netwerk/ipc/DocumentLoadListener.cpp b/netwerk/ipc/DocumentLoadListener.cpp
index d9783f7852a3..6d94893fb020 100644
--- a/netwerk/ipc/DocumentLoadListener.cpp
+++ b/netwerk/ipc/DocumentLoadListener.cpp
@@ -912,7 +912,7 @@ auto DocumentLoadListener::Open(nsDocShellLoadState* aLoadState,
   if (aLoadState->GetRemoteTypeOverride()) {
     if (!mIsDocumentLoad || !NS_IsAboutBlank(aLoadState->URI()) ||
         !loadingContext->IsTopContent() ||
-        aLoadState->GetEffectiveTriggeringRemoteType() != NOT_REMOTE_TYPE ||
+        !aLoadState->GetEffectiveTriggeringRemoteType().IsNotRemote() ||
         aLoadState->LoadIsFromSessionHistory()) {
       LOG(
           ("DocumentLoadListener::Open with invalid remoteTypeOverride "
@@ -2188,7 +2188,7 @@ bool DocumentLoadListener::MaybeTriggerProcessSwitch(
     return false;
   }
 
-  nsAutoCString currentRemoteType(NOT_REMOTE_TYPE);
+  RemoteType currentRemoteType = RemoteType::NotRemote();
   if (mContentParent) {
     currentRemoteType = mContentParent->GetRemoteType();
   }
@@ -2232,21 +2232,21 @@ bool DocumentLoadListener::MaybeTriggerProcessSwitch(
       gProcessIsolationLog, LogLevel::Verbose,
       ("CheckIsolationForNavigation -> current:(%s) remoteType:(%s) replace:%d "
        "group:%" PRIx64 " bfcache:%d shentry:%p newTab:%d",
-       currentRemoteType.get(), options.mRemoteType.get(),
-       options.mReplaceBrowsingContext, options.mSpecificGroupId,
-       options.mTryUseBFCache, options.mActiveSessionHistoryEntry.get(),
-       switchToNewTab));
+       currentRemoteType.Stringify().get(),
+       options.mRemoteType.Stringify().get(), options.mReplaceBrowsingContext,
+       options.mSpecificGroupId, options.mTryUseBFCache,
+       options.mActiveSessionHistoryEntry.get(), switchToNewTab));
 
   // Check if a process switch is needed.
   if (currentRemoteType == options.mRemoteType &&
       !options.mReplaceBrowsingContext && !switchToNewTab) {
     MOZ_LOG(gProcessIsolationLog, LogLevel::Info,
             ("Process Switch Abort: type (%s) is compatible",
-             options.mRemoteType.get()));
+             options.mRemoteType.Stringify().get()));
     return false;
   }
 
-  if (NS_WARN_IF(parentWindow && options.mRemoteType.IsEmpty())) {
+  if (NS_WARN_IF(parentWindow && options.mRemoteType.IsNotRemote())) {
     MOZ_LOG(gProcessIsolationLog, LogLevel::Error,
             ("Process Switch Abort: non-remote target process for subframe"));
     return false;
@@ -2254,8 +2254,7 @@ bool DocumentLoadListener::MaybeTriggerProcessSwitch(
 
   // ParentProcessDocumentChannel applies the same check to loads which started
   // in the parent, so do it here for loads switching into the parent.
-  if (options.mRemoteType == NOT_REMOTE_TYPE &&
-      currentRemoteType != NOT_REMOTE_TYPE) {
+  if (options.mRemoteType.IsNotRemote() && !currentRemoteType.IsNotRemote()) {
     nsCOMPtr<nsIURI> uri;
     MOZ_ALWAYS_SUCCEEDS(NS_GetFinalChannelURI(mChannel, getter_AddRefs(uri)));
     if (NS_WARN_IF(!nsDocShell::CanLoadInParentProcess(uri))) {
@@ -2266,7 +2265,7 @@ bool DocumentLoadListener::MaybeTriggerProcessSwitch(
     }
   }
 
-  *aWillSwitchToRemote = !options.mRemoteType.IsEmpty();
+  *aWillSwitchToRemote = !options.mRemoteType.IsNotRemote();
 
   // If we've decided to re-target this load into a new tab or window (see
   // `GetWhereToOpen`), do so before performing a process switch. This will
@@ -2380,7 +2379,7 @@ void DocumentLoadListener::TriggerProcessSwitch(
 
     MOZ_LOG(gProcessIsolationLog, LogLevel::Info,
             ("Process Switch: Changing Remoteness from '%s' to '%s'",
-             currentRemoteType.get(), aOptions.mRemoteType.get()));
+             currentRemoteType.get(), aOptions.mRemoteType.Stringify().get()));
   }
 
   // Stash our stream filter requests to pass to TriggerRedirectToRealChannel,
@@ -3356,7 +3355,7 @@ DocumentLoadListener::Delete() {
 }
 
 NS_IMETHODIMP
-DocumentLoadListener::GetRemoteType(nsACString& aRemoteType) {
+DocumentLoadListener::GetRemoteType(dom::RemoteType& aRemoteType) {
   // FIXME: The remote type here should be pulled from the remote process used
   // to create this DLL, not from the current `browsingContext`.
   RefPtr<CanonicalBrowsingContext> browsingContext =
@@ -3365,11 +3364,8 @@ DocumentLoadListener::GetRemoteType(nsACString& aRemoteType) {
     return NS_ERROR_UNEXPECTED;
   }
 
-  ErrorResult error;
-  browsingContext->GetCurrentRemoteType(aRemoteType, error);
-  if (error.Failed()) {
-    aRemoteType = NOT_REMOTE_TYPE;
-  }
+  dom::ContentParent* cp = browsingContext->GetContentParent();
+  aRemoteType = cp ? cp->GetRemoteType() : dom::RemoteType::NotRemote();
   return NS_OK;
 }
 
diff --git a/netwerk/ipc/DocumentLoadListener.h b/netwerk/ipc/DocumentLoadListener.h
index bf56b47a7392..6461112fdd69 100644
--- a/netwerk/ipc/DocumentLoadListener.h
+++ b/netwerk/ipc/DocumentLoadListener.h
@@ -9,6 +9,7 @@
 #include "mozilla/MozPromise.h"
 #include "mozilla/Variant.h"
 #include "mozilla/WeakPtr.h"
+#include "mozilla/dom/RemoteType.h"
 #include "mozilla/dom/SessionHistoryEntry.h"
 #include "mozilla/ipc/Endpoint.h"
 #include "mozilla/net/NeckoCommon.h"
@@ -608,7 +609,7 @@ class DocumentLoadListener : public nsIInterfaceRequestor,
   // channel to the final document.
   RefPtr<dom::ParentProcessChannelHandle> mParentProcessChannelHandle;
 
-  Maybe<nsCString> mRemoteTypeOverride;
+  Maybe<dom::RemoteType> mRemoteTypeOverride;
 
   // The ContentParent which this channel is currently connected to, or nullptr
   // if connected to the parent process.
diff --git a/netwerk/ipc/NeckoChannelParams.ipdlh b/netwerk/ipc/NeckoChannelParams.ipdlh
index 2233543b6610..b6483ea7ae36 100644
--- a/netwerk/ipc/NeckoChannelParams.ipdlh
+++ b/netwerk/ipc/NeckoChannelParams.ipdlh
@@ -47,6 +47,7 @@ using mozilla::dom::UserNavigationInvolvement from "mozilla/dom/UserNavigationIn
 using mozilla::RFPTargetSet from "nsRFPService.h";
 using PropertiesFile from "nsContentUtils.h";
 [RefCounted] using mozilla::dom::ParentProcessChannelHandle from "mozilla/dom/ParentProcessChannelHandle.h";
+using struct mozilla::dom::RemoteType from "mozilla/dom/RemoteType.h";
 
 namespace mozilla {
 namespace net {
@@ -124,7 +125,7 @@ struct LoadInfoArgs
   PrincipalInfo?              principalToInheritInfo;
   PrincipalInfo?              topLevelPrincipalInfo;
   URIParams?                  resultPrincipalURI;
-  nsCString                   triggeringRemoteType;
+  RemoteType                  triggeringRemoteType;
   nsID                        sandboxedNullPrincipalID;
   uint32_t                    securityFlags;
   uint32_t                    sandboxFlags;
diff --git a/netwerk/ipc/NeckoParent.cpp b/netwerk/ipc/NeckoParent.cpp
index e414fac0fb1d..2e9fd59c8a79 100644
--- a/netwerk/ipc/NeckoParent.cpp
+++ b/netwerk/ipc/NeckoParent.cpp
@@ -754,20 +754,22 @@ mozilla::ipc::IPCResult NeckoParent::RecvEnsureHSTSData(
 mozilla::ipc::IPCResult NeckoParent::RecvGetPageThumbStream(
     nsIURI* aURI, const LoadInfoArgs& aLoadInfoArgs,
     GetPageThumbStreamResolver&& aResolver) {
+  const dom::RemoteType& remoteType =
+      ContentParent::Cast(Manager())->GetRemoteType();
+
   // Only the privileged about content process is allowed to access
   // things over the moz-page-thumb protocol. Any other content process
   // that tries to send this should have been blocked via the
   // ScriptSecurityManager, but if somehow the process has been tricked into
   // sending this message, we send IPC_FAIL in order to crash that
   // likely-compromised content process.
-  if (mozilla::ipc::ActorCast<ContentParent>(Manager())->GetRemoteType() !=
-      PRIVILEGEDABOUT_REMOTE_TYPE) {
+  if (!remoteType.IsPrivilegedAbout()) {
     return IPC_FAIL(this, "Wrong process type");
   }
 
   nsCOMPtr<nsILoadInfo> loadInfo;
-  nsresult rv = mozilla::ipc::LoadInfoArgsToLoadInfo(
-      aLoadInfoArgs, PRIVILEGEDABOUT_REMOTE_TYPE, getter_AddRefs(loadInfo));
+  nsresult rv = mozilla::ipc::LoadInfoArgsToLoadInfo(aLoadInfoArgs, remoteType,
+                                                     getter_AddRefs(loadInfo));
   if (NS_FAILED(rv)) {
     return IPC_FAIL(this, "moz-page-thumb request must include loadInfo");
   }
@@ -806,20 +808,22 @@ mozilla::ipc::IPCResult NeckoParent::RecvGetPageThumbStream(
 mozilla::ipc::IPCResult NeckoParent::RecvGetMozNewTabWallpaperStream(
     nsIURI* aURI, const LoadInfoArgs& aLoadInfoArgs,
     GetMozNewTabWallpaperStreamResolver&& aResolver) {
+  const dom::RemoteType& remoteType =
+      ContentParent::Cast(Manager())->GetRemoteType();
+
   // Only the privileged about content process is allowed to access
   // things over the moz-newtab-wallpaper protocol. Any other content process
   // that tries to send this should have been blocked via the
   // ScriptSecurityManager, but if somehow the process has been tricked into
   // sending this message, we send IPC_FAIL in order to crash that
   // likely-compromised content process.
-  if (mozilla::ipc::ActorCast<ContentParent>(Manager())->GetRemoteType() !=
-      PRIVILEGEDABOUT_REMOTE_TYPE) {
+  if (!remoteType.IsPrivilegedAbout()) {
     return IPC_FAIL(this, "Wrong process type");
   }
 
   nsCOMPtr<nsILoadInfo> loadInfo;
-  nsresult rv = mozilla::ipc::LoadInfoArgsToLoadInfo(
-      aLoadInfoArgs, PRIVILEGEDABOUT_REMOTE_TYPE, getter_AddRefs(loadInfo));
+  nsresult rv = mozilla::ipc::LoadInfoArgsToLoadInfo(aLoadInfoArgs, remoteType,
+                                                     getter_AddRefs(loadInfo));
   if (NS_FAILED(rv)) {
     return IPC_FAIL(this, "moz-newtab-wallpaper request must include loadInfo");
   }
@@ -860,7 +864,7 @@ mozilla::ipc::IPCResult NeckoParent::RecvGetPageIconStream(
     nsIURI* aURI, const LoadInfoArgs& aLoadInfoArgs,
     GetPageIconStreamResolver&& aResolver) {
 #ifdef MOZ_PLACES
-  const nsACString& remoteType =
+  const dom::RemoteType& remoteType =
       ContentParent::Cast(Manager())->GetRemoteType();
 
   // Only the privileged about content process is allowed to access
@@ -869,7 +873,7 @@ mozilla::ipc::IPCResult NeckoParent::RecvGetPageIconStream(
   // ScriptSecurityManager, but if somehow the process has been tricked into
   // sending this message, we send IPC_FAIL in order to crash that
   // likely-compromised content process.
-  if (remoteType != PRIVILEGEDABOUT_REMOTE_TYPE) {
+  if (!remoteType.IsPrivilegedAbout()) {
     return IPC_FAIL(this, "Wrong process type");
   }
 
diff --git a/netwerk/ipc/ParentChannelWrapper.cpp b/netwerk/ipc/ParentChannelWrapper.cpp
index f3edf4dea37c..912bd3027c6d 100644
--- a/netwerk/ipc/ParentChannelWrapper.cpp
+++ b/netwerk/ipc/ParentChannelWrapper.cpp
@@ -93,8 +93,8 @@ NS_IMETHODIMP
 ParentChannelWrapper::Delete() { return NS_OK; }
 
 NS_IMETHODIMP
-ParentChannelWrapper::GetRemoteType(nsACString& aRemoteType) {
-  aRemoteType = NOT_REMOTE_TYPE;
+ParentChannelWrapper::GetRemoteType(mozilla::dom::RemoteType& aRemoteType) {
+  aRemoteType = mozilla::dom::RemoteType::NotRemote();
   return NS_OK;
 }
 
diff --git a/netwerk/ipc/SocketProcessHost.cpp b/netwerk/ipc/SocketProcessHost.cpp
index 9a69f0e73ebb..710de656a8e4 100644
--- a/netwerk/ipc/SocketProcessHost.cpp
+++ b/netwerk/ipc/SocketProcessHost.cpp
@@ -73,7 +73,7 @@ bool SocketProcessHost::Launch() {
 
   SharedPreferenceSerializer prefSerializer;
   if (!prefSerializer.SerializeToSharedMemory(GeckoProcessType_VR,
-                                              /* remoteType */ ""_ns)) {
+                                              /* remoteType */ {})) {
     return false;
   }
   prefSerializer.AddSharedPrefCmdLineArgs(*this, extraArgs);
diff --git a/netwerk/protocol/file/nsFileChannel.cpp b/netwerk/protocol/file/nsFileChannel.cpp
index d47e9acda151..f163633a4d67 100644
--- a/netwerk/protocol/file/nsFileChannel.cpp
+++ b/netwerk/protocol/file/nsFileChannel.cpp
@@ -572,7 +572,7 @@ nsresult nsFileChannel::MaybeSendFileOpenNotification() {
 
 /* static */
 nsresult nsFileChannel::DoNotifyFileChannelOpened(
-    const nsACString& aRemoteType,
+    const mozilla::dom::RemoteType& aRemoteType,
     const mozilla::net::FileChannelInfo& aFileChannelInfo) {
   nsCOMPtr<nsIObserverService> obsService = components::Observer::Service();
   if (!obsService) {
diff --git a/netwerk/protocol/file/nsFileChannel.h b/netwerk/protocol/file/nsFileChannel.h
index 3174798ce198..e43325f9c75e 100644
--- a/netwerk/protocol/file/nsFileChannel.h
+++ b/netwerk/protocol/file/nsFileChannel.h
@@ -33,7 +33,7 @@ class nsFileChannel : public nsBaseChannel,
   nsresult Init();
 
   static nsresult DoNotifyFileChannelOpened(
-      const nsACString& aRemoteType,
+      const mozilla::dom::RemoteType& aRemoteType,
       const mozilla::net::FileChannelInfo& aFileChannelInfo);
 
  protected:
diff --git a/netwerk/protocol/http/HttpChannelParent.cpp b/netwerk/protocol/http/HttpChannelParent.cpp
index 1048d59a6b1f..43d24cc06b13 100644
--- a/netwerk/protocol/http/HttpChannelParent.cpp
+++ b/netwerk/protocol/http/HttpChannelParent.cpp
@@ -479,6 +479,10 @@ bool HttpChannelParent::DoAsyncOpen(
     return false;
   }
 
+  if (!CanSend()) {
+    return false;
+  }
+
   LOG(("HttpChannelParent RecvAsyncOpen [this=%p uri=%s, gid=%" PRIu64
        " browserid=%" PRIx64 "]\n",
        this, aURI->GetSpecOrDefault().get(), aChannelId, aBrowserId));
@@ -488,11 +492,10 @@ bool HttpChannelParent::DoAsyncOpen(
                   aURI->GetSpecOrDefault(), aChannelId);
 
   nsresult rv;
-  nsAutoCString remoteType;
-  rv = GetRemoteType(remoteType);
-  if (NS_FAILED(rv)) {
-    return SendFailedAsyncOpen(rv);
-  }
+
+  dom::PContentParent* pcp = Manager()->Manager();
+  const dom::RemoteType& remoteType =
+      static_cast<dom::ContentParent*>(pcp)->GetRemoteType();
 
   nsCOMPtr<nsILoadInfo> loadInfo;
   rv = mozilla::ipc::LoadInfoArgsToLoadInfo(aLoadInfoArgs, remoteType,
@@ -1796,7 +1799,7 @@ HttpChannelParent::Delete() {
 }
 
 NS_IMETHODIMP
-HttpChannelParent::GetRemoteType(nsACString& aRemoteType) {
+HttpChannelParent::GetRemoteType(dom::RemoteType& aRemoteType) {
   if (!CanSend()) {
     return NS_ERROR_UNEXPECTED;
   }
diff --git a/security/sandbox/linux/glue/SandboxPrefBridge.cpp b/security/sandbox/linux/glue/SandboxPrefBridge.cpp
index 3d4314708449..60f7a77b34fd 100644
--- a/security/sandbox/linux/glue/SandboxPrefBridge.cpp
+++ b/security/sandbox/linux/glue/SandboxPrefBridge.cpp
@@ -6,7 +6,7 @@
 #include "mozilla/Preferences.h"
 #include "mozilla/SandboxSettings.h"
 #include "mozilla/dom/ContentChild.h"
-#include "mozilla/dom/ContentParent.h"  // for FILE_REMOTE_TYPE
+#include "mozilla/dom/ContentParent.h"
 
 namespace mozilla {
 
@@ -27,7 +27,7 @@ ContentProcessSandboxParams::ForThisProcess(
   // (Otherwise, mBrokerFd will remain -1 from the default ctor.)
 
   auto* cc = dom::ContentChild::GetSingleton();
-  params.mFileProcess = cc->GetRemoteType() == FILE_REMOTE_TYPE;
+  params.mFileProcess = cc->GetRemoteType().IsFile();
 
   nsAutoCString extraSyscalls;
   nsresult rv = Preferences::GetCString(
diff --git a/toolkit/components/backgroundhangmonitor/BackgroundHangMonitor.cpp b/toolkit/components/backgroundhangmonitor/BackgroundHangMonitor.cpp
index 7c08184911cf..297ead5fb28e 100644
--- a/toolkit/components/backgroundhangmonitor/BackgroundHangMonitor.cpp
+++ b/toolkit/components/backgroundhangmonitor/BackgroundHangMonitor.cpp
@@ -415,10 +415,10 @@ void BackgroundHangThread::ReportHang(TimeDuration aHangTime,
   // Recovered from a hang; called on the monitor thread
   // mManager->mLock IS locked
 
-  HangDetails hangDetails(aHangTime,
-                          nsDependentCString(XRE_GetProcessTypeString()),
-                          NOT_REMOTE_TYPE, mThreadName, mRunnableName,
-                          std::move(mHangStack), std::move(mAnnotations));
+  HangDetails hangDetails(
+      aHangTime, nsDependentCString(XRE_GetProcessTypeString()),
+      dom::RemoteType::NotRemote().Stringify(), mThreadName, mRunnableName,
+      std::move(mHangStack), std::move(mAnnotations));
 
   PersistedToDisk persistedToDisk = aPersistedToDisk;
   if (aPersistedToDisk == PersistedToDisk::Yes && XRE_IsParentProcess() &&
diff --git a/toolkit/components/backgroundhangmonitor/HangDetails.cpp b/toolkit/components/backgroundhangmonitor/HangDetails.cpp
index b9d02263a43b..a6674f5efcd4 100644
--- a/toolkit/components/backgroundhangmonitor/HangDetails.cpp
+++ b/toolkit/components/backgroundhangmonitor/HangDetails.cpp
@@ -11,7 +11,6 @@
 #include "mozilla/FileUtils.h"
 #include "mozilla/gfx/GPUParent.h"
 #include "mozilla/dom/ContentChild.h"
-#include "mozilla/dom/ContentParent.h"  // For RemoteTypePrefix
 #include "mozilla/FileUtils.h"
 #include "mozilla/SchedulerGroup.h"
 #include "mozilla/GfxMessageUtils.h"  // For ParamTraits<GeckoProcessType>
@@ -290,10 +289,10 @@ void nsHangDetails::Submit() {
           case GeckoProcessType_Content: {
             auto cc = dom::ContentChild::GetSingleton();
             if (cc) {
-              // Use the prefix so we don't get URIs from Fission isolated
+              // Use the kind so we don't get URIs from Fission isolated
               // processes.
-              hangDetails->mDetails.remoteType().Assign(
-                  dom::RemoteTypePrefix(cc->GetRemoteType()));
+              hangDetails->mDetails.remoteType() =
+                  cc->GetRemoteType().StringifyKind();
               (void)cc->SendBHRThreadHang(hangDetails->mDetails);
             }
             break;
diff --git a/toolkit/components/extensions/ExtensionPolicyService.cpp b/toolkit/components/extensions/ExtensionPolicyService.cpp
index ac8206a409c1..aa472c4247fc 100644
--- a/toolkit/components/extensions/ExtensionPolicyService.cpp
+++ b/toolkit/components/extensions/ExtensionPolicyService.cpp
@@ -164,7 +164,7 @@ bool ExtensionPolicyService::IsExtensionProcess() const {
 
   if (isRemote && XRE_IsContentProcess()) {
     auto& remoteType = dom::ContentChild::GetSingleton()->GetRemoteType();
-    return remoteType == EXTENSION_REMOTE_TYPE;
+    return remoteType.IsExtension();
   }
   return !isRemote && XRE_IsParentProcess();
 }
diff --git a/toolkit/components/extensions/webrequest/ChannelWrapper.cpp b/toolkit/components/extensions/webrequest/ChannelWrapper.cpp
index 0a9f39cb9c08..7f05548d4e2f 100644
--- a/toolkit/components/extensions/webrequest/ChannelWrapper.cpp
+++ b/toolkit/components/extensions/webrequest/ChannelWrapper.cpp
@@ -893,8 +893,8 @@ already_AddRefed<nsITraceableChannel> ChannelWrapper::GetTraceableChannel(
     if (aContentParent) {
       RefPtr<BrowsingContextGroup> group =
           BrowsingContextGroup::GetExisting(aAddon.GetBrowsingContextGroupId());
-      if (!group ||
-          group->GetHostProcess(EXTENSION_REMOTE_TYPE) != aContentParent) {
+      if (!group || group->GetHostProcess(RemoteType(
+                        RemoteType::Kind::Extension)) != aContentParent) {
         return nullptr;
       }
     } else {
diff --git a/toolkit/components/glean/bindings/private/Labeled.cpp b/toolkit/components/glean/bindings/private/Labeled.cpp
index 15a73a6ca23e..c2d0ab77df58 100644
--- a/toolkit/components/glean/bindings/private/Labeled.cpp
+++ b/toolkit/components/glean/bindings/private/Labeled.cpp
@@ -184,10 +184,10 @@ nsCString GetProcessTypeForTelemetry() {
   if (processType.EqualsLiteral("tab")) {
     auto* cc = mozilla::dom::ContentChild::GetSingleton();
     if (cc) {
-      const nsACString& remoteType = cc->GetRemoteType();
-      if (remoteType == EXTENSION_REMOTE_TYPE) {
+      const auto& remoteType = cc->GetRemoteType();
+      if (remoteType.IsExtension()) {
         processType.AssignLiteral("extension");
-      } else if (remoteType == INFERENCE_REMOTE_TYPE) {
+      } else if (remoteType.IsInference()) {
         processType.AssignLiteral("inference");
       }
       // Otherwise keep "tab" for regular content processes
diff --git a/toolkit/components/glean/ipc/FOGIPC.cpp b/toolkit/components/glean/ipc/FOGIPC.cpp
index 84530f8a2eb3..9b881d98a6df 100644
--- a/toolkit/components/glean/ipc/FOGIPC.cpp
+++ b/toolkit/components/glean/ipc/FOGIPC.cpp
@@ -340,8 +340,7 @@ void RecordPowerMetrics() {
   if (XRE_IsContentProcess()) {
     auto* cc = mozilla::dom::ContentChild::GetSingleton();
     if (cc) {
-      type.Assign(mozilla::dom::RemoteTypePrefix(cc->GetRemoteType()));
-      if (StringBeginsWith(type, WEB_REMOTE_TYPE)) {
+      if (cc->GetRemoteType().IsWeb()) {
         type.AssignLiteral("web");
         switch (cc->GetProcessPriority()) {
           case hal::PROCESS_PRIORITY_BACKGROUND:
@@ -364,9 +363,11 @@ void RecordPowerMetrics() {
             MOZ_ASSERT_UNREACHABLE("Unsuppored process type for cpu time");
             break;
         }
-      } else if (type == INFERENCE_REMOTE_TYPE) {
+      } else if (cc->GetRemoteType().IsInference()) {
         type.AssignLiteral("inference");
         gThisProcessType = ProcessType::eInferenceProcess;
+      } else {
+        type = cc->GetRemoteType().StringifyKind();
       }
       GetTrackerType(trackerType);
     } else {
diff --git a/toolkit/components/ml/backends/llama/LlamaRunner.cpp b/toolkit/components/ml/backends/llama/LlamaRunner.cpp
index fbf8e7726591..c59ea39f4a5b 100644
--- a/toolkit/components/ml/backends/llama/LlamaRunner.cpp
+++ b/toolkit/components/ml/backends/llama/LlamaRunner.cpp
@@ -684,8 +684,7 @@ bool LlamaRunner::InInferenceProcess(JSContext*, JSObject*) {
   if (!ContentChild::GetSingleton()) {
     return false;
   }
-  return ContentChild::GetSingleton()->GetRemoteType().Equals(
-      INFERENCE_REMOTE_TYPE);
+  return ContentChild::GetSingleton()->GetRemoteType().IsInference();
 }
 
 class MetadataCallback final : public nsIFileMetadataCallback {
diff --git a/toolkit/modules/E10SUtils.sys.mjs b/toolkit/modules/E10SUtils.sys.mjs
index 08ee146f3a99..2948e843daf2 100644
--- a/toolkit/modules/E10SUtils.sys.mjs
+++ b/toolkit/modules/E10SUtils.sys.mjs
@@ -429,18 +429,9 @@ export var E10SUtils = {
     return [tabPid, ...pids];
   },
 
-  /**
-   * The suffix after a `=` in a remoteType is dynamic, and used to control the
-   * process pool to use. The C++ version of this method is mozilla::dom::RemoteTypePrefix().
-   */
-  remoteTypePrefix(aRemoteType) {
-    return aRemoteType.split("=")[0];
-  },
-
   /**
    * There are various types of remote types that are for web content processes, but
-   * they all start with "web". The C++ version of this method is
-   * mozilla::dom::IsWebRemoteType().
+   * they all start with "web". The C++ version of this method is RemoteType::IsWeb().
    */
   isWebRemoteType(aRemoteType) {
     return aRemoteType.startsWith(WEB_REMOTE_TYPE);
diff --git a/toolkit/xre/nsAppRunner.cpp b/toolkit/xre/nsAppRunner.cpp
index 1cf5753154ce..fb22d2956232 100644
--- a/toolkit/xre/nsAppRunner.cpp
+++ b/toolkit/xre/nsAppRunner.cpp
@@ -1270,9 +1270,9 @@ nsXULAppInfo::GetUniqueProcessID(uint64_t* aResult) {
 NS_IMETHODIMP
 nsXULAppInfo::GetRemoteType(nsACString& aRemoteType) {
   if (XRE_IsContentProcess()) {
-    aRemoteType = ContentChild::GetSingleton()->GetRemoteType();
+    aRemoteType = ContentChild::GetSingleton()->GetRemoteType().Stringify();
   } else {
-    aRemoteType = NOT_REMOTE_TYPE;
+    aRemoteType = dom::RemoteType::NotRemote().Stringify();
   }
 
   return NS_OK;
diff --git a/toolkit/xre/nsEmbedFunctions.cpp b/toolkit/xre/nsEmbedFunctions.cpp
index 22939d60120c..6d29b4232ff9 100644
--- a/toolkit/xre/nsEmbedFunctions.cpp
+++ b/toolkit/xre/nsEmbedFunctions.cpp
@@ -684,8 +684,8 @@ already_AddRefed<TestShellParent> GetOrCreateTestShellParent() {
     // this and you're sure you wouldn't be better off writing a "browser"
     // chrome mochitest where you can have multiple types of content
     // processes.
-    TestShellContentParent() =
-        ContentParent::GetNewOrUsedBrowserProcess(DEFAULT_REMOTE_TYPE);
+    TestShellContentParent() = ContentParent::GetNewOrUsedBrowserProcess(
+        mozilla::dom::RemoteType::SharedWeb({}));
   } else if (TestShellContentParent()->IsShuttingDown()) {
     return nullptr;
   }
diff --git a/uriloader/exthandler/nsExternalProtocolHandler.cpp b/uriloader/exthandler/nsExternalProtocolHandler.cpp
index 5d77ca6ba57c..f19813140759 100644
--- a/uriloader/exthandler/nsExternalProtocolHandler.cpp
+++ b/uriloader/exthandler/nsExternalProtocolHandler.cpp
@@ -455,7 +455,8 @@ NS_IMETHODIMP nsExtProtocolChannel::Delete() {
   return NS_OK;
 }
 
-NS_IMETHODIMP nsExtProtocolChannel::GetRemoteType(nsACString& aRemoteType) {
+NS_IMETHODIMP nsExtProtocolChannel::GetRemoteType(
+    mozilla::dom::RemoteType& aRemoteType) {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
diff --git a/xpcom/base/MemoryTelemetry.cpp b/xpcom/base/MemoryTelemetry.cpp
index 66d16ec9740a..ec24691653b0 100644
--- a/xpcom/base/MemoryTelemetry.cpp
+++ b/xpcom/base/MemoryTelemetry.cpp
@@ -161,7 +161,7 @@ void MemoryTelemetry::Poke() {
 
   if (XRE_IsContentProcess()) {
     auto& remoteType = dom::ContentChild::GetSingleton()->GetRemoteType();
-    if (remoteType == PREALLOC_REMOTE_TYPE) {
+    if (remoteType.IsPrealloc()) {
       // Preallocated processes should stay dormant and not run this telemetry
       // code.
       return;