diff --git a/dwds/debug_extension_mv3/web/background.dart b/dwds/debug_extension_mv3/web/background.dart
index a119d1a6b..10436c63e 100644
--- a/dwds/debug_extension_mv3/web/background.dart
+++ b/dwds/debug_extension_mv3/web/background.dart
@@ -15,6 +15,7 @@ import 'package:js/js.dart';
 import 'data_types.dart';
 import 'debug_session.dart';
 import 'chrome_api.dart';
+import 'cross_extension_communication.dart';
 import 'lifeline_ports.dart';
 import 'logger.dart';
 import 'messaging.dart';
@@ -29,7 +30,15 @@ void main() {
 }
 
 void _registerListeners() {
-  chrome.runtime.onMessage.addListener(allowInterop(_handleRuntimeMessages));
+  chrome.runtime.onMessage.addListener(
+    allowInterop(_handleRuntimeMessages),
+  );
+  // The only extension allowed to send messages to this extension is the
+  // AngularDart DevTools extension. Its permission is set in the manifest.json
+  // externally_connectable field.
+  chrome.runtime.onMessageExternal.addListener(
+    allowInterop(handleMessagesFromAngularDartDevTools),
+  );
   chrome.tabs.onRemoved
       .addListener(allowInterop((tabId, _) => maybeRemoveLifelinePort(tabId)));
   // Update the extension icon on tab navigation:
diff --git a/dwds/debug_extension_mv3/web/chrome_api.dart b/dwds/debug_extension_mv3/web/chrome_api.dart
index 76114fd4a..803e13082 100644
--- a/dwds/debug_extension_mv3/web/chrome_api.dart
+++ b/dwds/debug_extension_mv3/web/chrome_api.dart
@@ -176,6 +176,8 @@ class Runtime {
   external ConnectionHandler get onConnect;
 
   external OnMessageHandler get onMessage;
+
+  external OnMessageHandler get onMessageExternal;
 }
 
 @JS()
diff --git a/dwds/debug_extension_mv3/web/cross_extension_communication.dart b/dwds/debug_extension_mv3/web/cross_extension_communication.dart
new file mode 100644
index 000000000..f62143bb4
--- /dev/null
+++ b/dwds/debug_extension_mv3/web/cross_extension_communication.dart
@@ -0,0 +1,161 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+@JS()
+library cross_extension_communication;
+
+import 'package:js/js.dart';
+
+import 'chrome_api.dart';
+import 'data_types.dart';
+import 'debug_session.dart';
+import 'logger.dart';
+import 'storage.dart';
+import 'web_api.dart';
+
+// The only extension allowed to communicate with this extension is the
+// AngularDart DevTools extension.
+//
+// This ID is used to send messages to AngularDart DevTools, while the
+// externally_connectable field in the manifest.json allows AngularDart DevTools
+// to send messages to this extension.
+const _angularDartDevToolsId = 'nbkbficgbembimioedhceniahniffgpl';
+
+// A set of events to forward to the AngularDart DevTools extension.
+final _eventsForAngularDartDevTools = {
+  'Overlay.inspectNodeRequested',
+  'dwds.encodedUri',
+};
+
+void handleMessagesFromAngularDartDevTools(
+    dynamic jsRequest, MessageSender sender, Function sendResponse) async {
+  if (jsRequest == null) return;
+  final message = jsRequest as ExternalExtensionMessage;
+  if (message.name == 'chrome.debugger.sendCommand') {
+    _forwardCommandToChromeDebugger(message, sendResponse);
+  } else if (message.name == 'dwds.encodedUri') {
+    _respondWithEncodedUri(message.tabId, sendResponse);
+  } else if (message.name == 'dwds.startDebugging') {
+    attachDebugger(message.tabId, trigger: Trigger.angularDartDevTools);
+    sendResponse(true);
+  } else {
+    sendResponse(
+        ErrorResponse()..error = 'Unknown message name: ${message.name}');
+  }
+}
+
+void maybeForwardMessageToAngularDartDevTools(
+    {required String method, required dynamic params, required int tabId}) {
+  if (!_eventsForAngularDartDevTools.contains(method)) return;
+
+  final message = method.startsWith('dwds')
+      ? _dwdsEventMessage(method: method, params: params, tabId: tabId)
+      : _debugEventMessage(method: method, params: params, tabId: tabId);
+
+  _forwardMessageToAngularDartDevTools(message);
+}
+
+void _forwardCommandToChromeDebugger(
+    ExternalExtensionMessage message, Function sendResponse) {
+  try {
+    final options = message.options as SendCommandOptions;
+    chrome.debugger.sendCommand(
+      Debuggee(tabId: message.tabId),
+      options.method,
+      options.commandParams,
+      allowInterop(
+          ([result]) => _respondWithChromeResult(result, sendResponse)),
+    );
+  } catch (e) {
+    sendResponse(ErrorResponse()..error = '$e');
+  }
+}
+
+void _respondWithChromeResult(Object? chromeResult, Function sendResponse) {
+  // No result indicates that an error occurred.
+  if (chromeResult == null) {
+    sendResponse(ErrorResponse()
+      ..error = JSON.stringify(
+        chrome.runtime.lastError ?? 'Unknown error.',
+      ));
+  } else {
+    sendResponse(chromeResult);
+  }
+}
+
+void _respondWithEncodedUri(int tabId, Function sendResponse) async {
+  final encodedUri = await fetchStorageObject<EncodedUri>(
+      type: StorageObject.encodedUri, tabId: tabId);
+  sendResponse(encodedUri ?? '');
+}
+
+void _forwardMessageToAngularDartDevTools(ExternalExtensionMessage message) {
+  chrome.runtime.sendMessage(
+    _angularDartDevToolsId,
+    message,
+    /* options */ null,
+    allowInterop(([result]) => _checkForErrors(result, message.name)),
+  );
+}
+
+void _checkForErrors(Object? chromeResult, String messageName) {
+  // No result indicates that an error occurred.
+  if (chromeResult == null) {
+    final errorMessage = chrome.runtime.lastError?.message ?? 'Unknown error.';
+    debugWarn('Error forwarding $messageName: $errorMessage');
+  }
+}
+
+ExternalExtensionMessage _debugEventMessage({
+  required String method,
+  required dynamic params,
+  required int tabId,
+}) =>
+    ExternalExtensionMessage(
+      name: 'chrome.debugger.event',
+      tabId: tabId,
+      options: DebugEvent(method: method, params: params),
+    );
+
+ExternalExtensionMessage _dwdsEventMessage({
+  required String method,
+  required dynamic params,
+  required int tabId,
+}) =>
+    ExternalExtensionMessage(
+      name: method,
+      tabId: tabId,
+      options: params,
+    );
+
+// This message is used for cross-extension communication between this extension
+// and the AngularDart DevTools extension.
+@JS()
+@anonymous
+class ExternalExtensionMessage {
+  external int get tabId;
+  external String get name;
+  external dynamic get options;
+  external factory ExternalExtensionMessage(
+      {required int tabId, required String name, required dynamic options});
+}
+
+@JS()
+@anonymous
+class DebugEvent {
+  external factory DebugEvent({String method, Object? params});
+}
+
+@JS()
+@anonymous
+class SendCommandOptions {
+  external String get method;
+  external Object get commandParams;
+}
+
+@JS()
+@anonymous
+class ErrorResponse {
+  external set error(String error);
+}
diff --git a/dwds/debug_extension_mv3/web/data_serializers.dart b/dwds/debug_extension_mv3/web/data_serializers.dart
index 9c4e31460..164b02602 100644
--- a/dwds/debug_extension_mv3/web/data_serializers.dart
+++ b/dwds/debug_extension_mv3/web/data_serializers.dart
@@ -21,6 +21,7 @@ part 'data_serializers.g.dart';
   DevToolsOpener,
   DevToolsUrl,
   DevToolsRequest,
+  EncodedUri,
   ExtensionEvent,
   ExtensionRequest,
   ExtensionResponse,
diff --git a/dwds/debug_extension_mv3/web/data_serializers.g.dart b/dwds/debug_extension_mv3/web/data_serializers.g.dart
index 7c15ed146..724ebcc4b 100644
--- a/dwds/debug_extension_mv3/web/data_serializers.g.dart
+++ b/dwds/debug_extension_mv3/web/data_serializers.g.dart
@@ -14,6 +14,7 @@ Serializers _$serializers = (new Serializers().toBuilder()
       ..add(DevToolsOpener.serializer)
       ..add(DevToolsRequest.serializer)
       ..add(DevToolsUrl.serializer)
+      ..add(EncodedUri.serializer)
       ..add(ExtensionEvent.serializer)
       ..add(ExtensionRequest.serializer)
       ..add(ExtensionResponse.serializer)
diff --git a/dwds/debug_extension_mv3/web/data_types.dart b/dwds/debug_extension_mv3/web/data_types.dart
index eb22eb4e7..5065e3e56 100644
--- a/dwds/debug_extension_mv3/web/data_types.dart
+++ b/dwds/debug_extension_mv3/web/data_types.dart
@@ -35,6 +35,18 @@ abstract class DevToolsOpener
   bool get newWindow;
 }
 
+// TODO(elliette): Standardize on uri or url here and across DWDS, instead of a
+// combination of both.
+abstract class EncodedUri implements Built<EncodedUri, EncodedUriBuilder> {
+  static Serializer<EncodedUri> get serializer => _$encodedUriSerializer;
+
+  factory EncodedUri([Function(EncodedUriBuilder) updates]) = _$EncodedUri;
+
+  EncodedUri._();
+
+  String get uri;
+}
+
 abstract class DevToolsUrl implements Built<DevToolsUrl, DevToolsUrlBuilder> {
   static Serializer<DevToolsUrl> get serializer => _$devToolsUrlSerializer;
 
diff --git a/dwds/debug_extension_mv3/web/data_types.g.dart b/dwds/debug_extension_mv3/web/data_types.g.dart
index 34c78b418..a625af3e2 100644
--- a/dwds/debug_extension_mv3/web/data_types.g.dart
+++ b/dwds/debug_extension_mv3/web/data_types.g.dart
@@ -10,6 +10,7 @@ Serializer<ConnectFailure> _$connectFailureSerializer =
     new _$ConnectFailureSerializer();
 Serializer<DevToolsOpener> _$devToolsOpenerSerializer =
     new _$DevToolsOpenerSerializer();
+Serializer<EncodedUri> _$encodedUriSerializer = new _$EncodedUriSerializer();
 Serializer<DevToolsUrl> _$devToolsUrlSerializer = new _$DevToolsUrlSerializer();
 Serializer<DebugStateChange> _$debugStateChangeSerializer =
     new _$DebugStateChangeSerializer();
@@ -108,6 +109,45 @@ class _$DevToolsOpenerSerializer
   }
 }
 
+class _$EncodedUriSerializer implements StructuredSerializer<EncodedUri> {
+  @override
+  final Iterable<Type> types = const [EncodedUri, _$EncodedUri];
+  @override
+  final String wireName = 'EncodedUri';
+
+  @override
+  Iterable<Object?> serialize(Serializers serializers, EncodedUri object,
+      {FullType specifiedType = FullType.unspecified}) {
+    final result = <Object?>[
+      'uri',
+      serializers.serialize(object.uri, specifiedType: const FullType(String)),
+    ];
+
+    return result;
+  }
+
+  @override
+  EncodedUri deserialize(Serializers serializers, Iterable<Object?> serialized,
+      {FullType specifiedType = FullType.unspecified}) {
+    final result = new EncodedUriBuilder();
+
+    final iterator = serialized.iterator;
+    while (iterator.moveNext()) {
+      final key = iterator.current! as String;
+      iterator.moveNext();
+      final Object? value = iterator.current;
+      switch (key) {
+        case 'uri':
+          result.uri = serializers.deserialize(value,
+              specifiedType: const FullType(String))! as String;
+          break;
+      }
+    }
+
+    return result.build();
+  }
+}
+
 class _$DevToolsUrlSerializer implements StructuredSerializer<DevToolsUrl> {
   @override
   final Iterable<Type> types = const [DevToolsUrl, _$DevToolsUrl];
@@ -386,6 +426,84 @@ class DevToolsOpenerBuilder
   }
 }
 
+class _$EncodedUri extends EncodedUri {
+  @override
+  final String uri;
+
+  factory _$EncodedUri([void Function(EncodedUriBuilder)? updates]) =>
+      (new EncodedUriBuilder()..update(updates))._build();
+
+  _$EncodedUri._({required this.uri}) : super._() {
+    BuiltValueNullFieldError.checkNotNull(uri, r'EncodedUri', 'uri');
+  }
+
+  @override
+  EncodedUri rebuild(void Function(EncodedUriBuilder) updates) =>
+      (toBuilder()..update(updates)).build();
+
+  @override
+  EncodedUriBuilder toBuilder() => new EncodedUriBuilder()..replace(this);
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(other, this)) return true;
+    return other is EncodedUri && uri == other.uri;
+  }
+
+  @override
+  int get hashCode {
+    return $jf($jc(0, uri.hashCode));
+  }
+
+  @override
+  String toString() {
+    return (newBuiltValueToStringHelper(r'EncodedUri')..add('uri', uri))
+        .toString();
+  }
+}
+
+class EncodedUriBuilder implements Builder<EncodedUri, EncodedUriBuilder> {
+  _$EncodedUri? _$v;
+
+  String? _uri;
+  String? get uri => _$this._uri;
+  set uri(String? uri) => _$this._uri = uri;
+
+  EncodedUriBuilder();
+
+  EncodedUriBuilder get _$this {
+    final $v = _$v;
+    if ($v != null) {
+      _uri = $v.uri;
+      _$v = null;
+    }
+    return this;
+  }
+
+  @override
+  void replace(EncodedUri other) {
+    ArgumentError.checkNotNull(other, 'other');
+    _$v = other as _$EncodedUri;
+  }
+
+  @override
+  void update(void Function(EncodedUriBuilder)? updates) {
+    if (updates != null) updates(this);
+  }
+
+  @override
+  EncodedUri build() => _build();
+
+  _$EncodedUri _build() {
+    final _$result = _$v ??
+        new _$EncodedUri._(
+            uri: BuiltValueNullFieldError.checkNotNull(
+                uri, r'EncodedUri', 'uri'));
+    replace(_$result);
+    return _$result;
+  }
+}
+
 class _$DevToolsUrl extends DevToolsUrl {
   @override
   final int tabId;
diff --git a/dwds/debug_extension_mv3/web/debug_session.dart b/dwds/debug_extension_mv3/web/debug_session.dart
index 02977643f..1b7a00023 100644
--- a/dwds/debug_extension_mv3/web/debug_session.dart
+++ b/dwds/debug_extension_mv3/web/debug_session.dart
@@ -24,6 +24,7 @@ import 'package:sse/client/sse_client.dart';
 import 'package:web_socket_channel/web_socket_channel.dart';
 
 import 'chrome_api.dart';
+import 'cross_extension_communication.dart';
 import 'data_serializers.dart';
 import 'data_types.dart';
 import 'logger.dart';
@@ -74,6 +75,7 @@ enum TabType {
 }
 
 enum Trigger {
+  angularDartDevTools,
   extensionPanel,
   extensionIcon,
 }
@@ -152,6 +154,9 @@ String _translateChromeError(String chromeErrorMessage) {
 
 Future<void> _onDebuggerEvent(
     Debuggee source, String method, Object? params) async {
+  maybeForwardMessageToAngularDartDevTools(
+      method: method, params: params, tabId: source.tabId);
+
   if (method == 'Runtime.executionContextCreated') {
     return _maybeConnectToDwds(source.tabId, params);
   }
@@ -237,13 +242,10 @@ void _routeDwdsEvent(String eventData, SocketClient client, int tabId) {
   if (message is ExtensionRequest) {
     _forwardDwdsEventToChromeDebugger(message, client, tabId);
   } else if (message is ExtensionEvent) {
-    switch (message.method) {
-      case 'dwds.encodedUri':
-        // TODO(elliette): Forward to external extensions.
-        break;
-      case 'dwds.devtoolsUri':
-        _openDevTools(message.params, dartAppTabId: tabId);
-        break;
+    maybeForwardMessageToAngularDartDevTools(
+        method: message.method, params: message.params, tabId: tabId);
+    if (message.method == 'dwds.devtoolsUri') {
+      _openDevTools(message.params, dartAppTabId: tabId);
     }
   }
 }
@@ -297,8 +299,10 @@ void _openDevTools(String devToolsUrl, {required int dartAppTabId}) async {
   }
   // Send the DevTools URL to the extension panels:
   _sendDevToolsUrlMessage(devToolsUrl, dartAppTabId: dartAppTabId);
-  // Open a separate tab / window if triggered through the extension icon:
-  if (debugSession.trigger == Trigger.extensionIcon) {
+  // Open a separate tab / window if triggered through the extension icon or
+  // through AngularDart DevTools:
+  if (debugSession.trigger == Trigger.extensionIcon ||
+      debugSession.trigger == Trigger.angularDartDevTools) {
     final devToolsOpener = await fetchStorageObject<DevToolsOpener>(
         type: StorageObject.devToolsOpener);
     final devToolsTab = await createTab(
diff --git a/dwds/debug_extension_mv3/web/manifest.json b/dwds/debug_extension_mv3/web/manifest.json
index 5481fea40..e44ed5828 100644
--- a/dwds/debug_extension_mv3/web/manifest.json
+++ b/dwds/debug_extension_mv3/web/manifest.json
@@ -6,6 +6,11 @@
     "action": {
         "default_icon": "static_assets/dart_dev.png"
     },
+    "externally_connectable": {
+        "ids": [
+            "nbkbficgbembimioedhceniahniffgpl"
+        ]
+    },
     "permissions": [
         "debugger",
         "notifications",
diff --git a/dwds/debug_extension_mv3/web/storage.dart b/dwds/debug_extension_mv3/web/storage.dart
index 5ba186005..31a3fd228 100644
--- a/dwds/debug_extension_mv3/web/storage.dart
+++ b/dwds/debug_extension_mv3/web/storage.dart
@@ -17,16 +17,8 @@ import 'logger.dart';
 
 enum StorageObject {
   debugInfo,
-  devToolsOpener;
-
-  String get keyName {
-    switch (this) {
-      case StorageObject.debugInfo:
-        return 'debugInfo';
-      case StorageObject.devToolsOpener:
-        return 'devToolsOpener';
-    }
-  }
+  devToolsOpener,
+  encodedUri;
 
   Persistance get persistance {
     switch (this) {
@@ -34,6 +26,8 @@ enum StorageObject {
         return Persistance.sessionOnly;
       case StorageObject.devToolsOpener:
         return Persistance.acrossSessions;
+      case StorageObject.encodedUri:
+        return Persistance.sessionOnly;
     }
   }
 }
@@ -103,6 +97,6 @@ StorageArea _getStorageArea(Persistance persistance) {
 }
 
 String _createStorageKey(StorageObject type, int? tabId) {
-  if (tabId == null) return type.keyName;
-  return '$tabId-${type.keyName}';
+  if (tabId == null) return type.name;
+  return '$tabId-${type.name}';
 }