diff --git a/packages/firebase_core/firebase_core/lib/firebase_core.dart b/packages/firebase_core/firebase_core/lib/firebase_core.dart
index 2f4df23c7206..466f74ad2acb 100644
--- a/packages/firebase_core/firebase_core/lib/firebase_core.dart
+++ b/packages/firebase_core/firebase_core/lib/firebase_core.dart
@@ -4,12 +4,16 @@
 // found in the LICENSE file.
 
 import 'package:firebase_core_platform_interface/firebase_core_platform_interface.dart'
-    hide MethodChannelFirebaseApp, MethodChannelFirebase;
+    hide MethodChannelFirebaseApp;
 import 'package:flutter/foundation.dart';
 
 export 'package:firebase_core_platform_interface/firebase_core_platform_interface.dart'
-    show FirebaseOptions, defaultFirebaseAppName, FirebaseException;
+    show
+        FirebaseApp,
+        FirebaseException,
+        FirebaseOptions,
+        FirebaseService,
+        defaultFirebaseAppName;
 
 part 'src/firebase.dart';
-part 'src/firebase_app.dart';
 part 'src/port_mapping.dart';
diff --git a/packages/firebase_core/firebase_core/lib/src/firebase.dart b/packages/firebase_core/firebase_core/lib/src/firebase.dart
index 3edce466264a..401669f41be6 100644
--- a/packages/firebase_core/firebase_core/lib/src/firebase.dart
+++ b/packages/firebase_core/firebase_core/lib/src/firebase.dart
@@ -20,12 +20,26 @@ class Firebase {
   static FirebasePlatform? delegatePackingProperty;
 
   static FirebasePlatform get _delegate {
-    return delegatePackingProperty ??= FirebasePlatform.instance;
+    final delegate = delegatePackingProperty;
+    if (delegate != null) {
+      return delegate;
+    }
+
+    // The platform interface cannot depend on the `MethodChannel`
+    // implementation (it has to stay usable without Flutter), which is why the
+    // default implementation is installed lazily here instead. Platform
+    // implementations register themselves, for example `FirebaseCoreWeb` does
+    // so from `registerWith`, in which case they are kept as is.
+    if (!FirebasePlatform.isRegistered) {
+      FirebasePlatform.instance = MethodChannelFirebase();
+    }
+
+    return delegatePackingProperty = FirebasePlatform.instance;
   }
 
   /// Returns a list of all [FirebaseApp] instances that have been created.
   static List<FirebaseApp> get apps {
-    return _delegate.apps.map(FirebaseApp._).toList(growable: false);
+    return _delegate.apps.map(FirebaseApp.fromPlatform).toList(growable: false);
   }
 
   /// Initializes a new [FirebaseApp] instance by [name] and [options] and
@@ -81,7 +95,7 @@ class Firebase {
       options: resolvedOptions,
     );
 
-    return FirebaseApp._(app);
+    return FirebaseApp.fromPlatform(app);
   }
 
   /// Returns a [FirebaseApp] instance.
@@ -91,7 +105,7 @@ class Firebase {
   static FirebaseApp app([String name = defaultFirebaseAppName]) {
     FirebaseAppPlatform app = _delegate.app(name);
 
-    return FirebaseApp._(app);
+    return FirebaseApp.fromPlatform(app);
   }
 
   // TODO(rrousselGit): remove ==/hashCode
diff --git a/packages/firebase_core/firebase_core_common/CHANGELOG.md b/packages/firebase_core/firebase_core_common/CHANGELOG.md
new file mode 100644
index 000000000000..ba35a0ae66fc
--- /dev/null
+++ b/packages/firebase_core/firebase_core_common/CHANGELOG.md
@@ -0,0 +1,12 @@
+## 0.1.0
+
+- Initial release.
+- Pure Dart types and platform interfaces extracted from
+  `firebase_core_platform_interface` (`FirebaseApp`, `FirebaseAppPlatform`,
+  `FirebaseOptions`, `FirebaseException`, `FirebasePlatform`, `FirebasePlugin`
+  and the shared exception helpers), so that Firebase Core platform
+  implementations can be consumed outside of Flutter.
+- `FirebasePlatform.instance` no longer defaults to the `MethodChannel`
+  implementation: implementations must register themselves (`FirebaseCoreWeb`
+  does so from `registerWith`) and `FirebasePlatform.isRegistered` allows
+  checking whether that happened.
diff --git a/packages/firebase_core/firebase_core_common/LICENSE b/packages/firebase_core/firebase_core_common/LICENSE
new file mode 100644
index 000000000000..000b4618d2bd
--- /dev/null
+++ b/packages/firebase_core/firebase_core_common/LICENSE
@@ -0,0 +1,27 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//    * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//    * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//    * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
\ No newline at end of file
diff --git a/packages/firebase_core/firebase_core_common/README.md b/packages/firebase_core/firebase_core_common/README.md
new file mode 100644
index 000000000000..6c4fabeb5aa5
--- /dev/null
+++ b/packages/firebase_core/firebase_core_common/README.md
@@ -0,0 +1,14 @@
+# firebase_core_common
+
+Pure Dart shared types and platform interfaces used by
+[`firebase_core`](https://pub.dev/packages/firebase_core) and its platform
+implementations.
+
+This package contains no Flutter dependency and never imports `package:flutter/*`
+(neither directly nor transitively). It exists so that platform implementations
+such as [`firebase_core_web`](https://pub.dev/packages/firebase_core_web) can be
+used outside of Flutter, for example in pure Dart web applications.
+
+It is not intended to be used directly by end users. The Flutter facing API is
+exposed by `firebase_core`, and `firebase_core_platform_interface` re-exports
+this package for backwards compatibility.
diff --git a/packages/firebase_core/firebase_core_common/lib/firebase_core_common.dart b/packages/firebase_core/firebase_core_common/lib/firebase_core_common.dart
new file mode 100644
index 000000000000..d453defe03bc
--- /dev/null
+++ b/packages/firebase_core/firebase_core_common/lib/firebase_core_common.dart
@@ -0,0 +1,24 @@
+// Copyright 2026, the Chromium 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.
+
+/// Pure Dart shared types and platform interfaces for Firebase Core.
+///
+/// This library must never import `package:flutter/*` or any library which
+/// does, so that Firebase Core platform implementations (such as
+/// `firebase_core_web`) can be used outside of Flutter, for example in
+/// pure Dart web applications.
+///
+/// `firebase_core_platform_interface` re-exports this library, so importing
+/// that package (directly or through `firebase_core`) keeps giving access to
+/// exactly the same types.
+library;
+
+export 'src/default_firebase_app_name.dart';
+export 'src/firebase_app.dart';
+export 'src/firebase_core_exceptions.dart';
+export 'src/firebase_exception.dart';
+export 'src/firebase_options.dart';
+export 'src/platform_interface/platform_interface_firebase.dart';
+export 'src/platform_interface/platform_interface_firebase_app.dart';
+export 'src/platform_interface/platform_interface_firebase_plugin.dart';
diff --git a/packages/firebase_core/firebase_core_common/lib/src/default_firebase_app_name.dart b/packages/firebase_core/firebase_core_common/lib/src/default_firebase_app_name.dart
new file mode 100644
index 000000000000..85120e1cff4c
--- /dev/null
+++ b/packages/firebase_core/firebase_core_common/lib/src/default_firebase_app_name.dart
@@ -0,0 +1,6 @@
+// Copyright 2026, the Chromium 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.
+
+/// The default Firebase application name.
+const String defaultFirebaseAppName = '[DEFAULT]';
diff --git a/packages/firebase_core/firebase_core/lib/src/firebase_app.dart b/packages/firebase_core/firebase_core_common/lib/src/firebase_app.dart
similarity index 86%
rename from packages/firebase_core/firebase_core/lib/src/firebase_app.dart
rename to packages/firebase_core/firebase_core_common/lib/src/firebase_app.dart
index 2dd14a80e0cc..81ce85df9421 100644
--- a/packages/firebase_core/firebase_core/lib/src/firebase_app.dart
+++ b/packages/firebase_core/firebase_core_common/lib/src/firebase_app.dart
@@ -3,12 +3,22 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of '../firebase_core.dart';
+import 'firebase_options.dart';
+import 'platform_interface/platform_interface_firebase_app.dart';
 
 /// Represents a single Firebase app instance.
 ///
 /// You can get an instance by calling [Firebase.app()].
 class FirebaseApp {
+  /// Creates a [FirebaseApp] from a [FirebaseAppPlatform] delegate.
+  ///
+  /// This is not intended to be used directly. On Flutter, use
+  /// `Firebase.initializeApp()` or `Firebase.app()` instead. When using the
+  /// platform interfaces directly, for example outside of Flutter, wrap the
+  /// result of [FirebasePlatform.initializeApp] with this constructor.
+  factory FirebaseApp.fromPlatform(FirebaseAppPlatform delegate) =>
+      FirebaseApp._(delegate);
+
   /// A [FirebaseApp] instance can only be accessed from a call to `app()` on
   /// [FirebaseCore].
   ///
diff --git a/packages/firebase_core/firebase_core_platform_interface/lib/src/firebase_core_exceptions.dart b/packages/firebase_core/firebase_core_common/lib/src/firebase_core_exceptions.dart
similarity index 96%
rename from packages/firebase_core/firebase_core_platform_interface/lib/src/firebase_core_exceptions.dart
rename to packages/firebase_core/firebase_core_common/lib/src/firebase_core_exceptions.dart
index c231518bf540..8144085912b0 100644
--- a/packages/firebase_core/firebase_core_platform_interface/lib/src/firebase_core_exceptions.dart
+++ b/packages/firebase_core/firebase_core_common/lib/src/firebase_core_exceptions.dart
@@ -3,7 +3,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of '../firebase_core_platform_interface.dart';
+import 'default_firebase_app_name.dart';
+import 'firebase_exception.dart';
 
 /// Throws a consistent cross-platform error message when usage of an app occurs but
 /// no app has been created.
diff --git a/packages/firebase_core/firebase_core_platform_interface/lib/src/firebase_exception.dart b/packages/firebase_core/firebase_core_common/lib/src/firebase_exception.dart
similarity index 97%
rename from packages/firebase_core/firebase_core_platform_interface/lib/src/firebase_exception.dart
rename to packages/firebase_core/firebase_core_common/lib/src/firebase_exception.dart
index 191e96d81a29..506211184b51 100644
--- a/packages/firebase_core/firebase_core_platform_interface/lib/src/firebase_exception.dart
+++ b/packages/firebase_core/firebase_core_common/lib/src/firebase_exception.dart
@@ -3,7 +3,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of '../firebase_core_platform_interface.dart';
+import 'package:meta/meta.dart';
 
 /// A generic class which provides exceptions in a Firebase-friendly format
 /// to users.
diff --git a/packages/firebase_core/firebase_core_platform_interface/lib/src/firebase_options.dart b/packages/firebase_core/firebase_core_common/lib/src/firebase_options.dart
similarity index 84%
rename from packages/firebase_core/firebase_core_platform_interface/lib/src/firebase_options.dart
rename to packages/firebase_core/firebase_core_common/lib/src/firebase_options.dart
index 3487164bb4a9..09fbdc8dd2d9 100644
--- a/packages/firebase_core/firebase_core_platform_interface/lib/src/firebase_options.dart
+++ b/packages/firebase_core/firebase_core_common/lib/src/firebase_options.dart
@@ -3,8 +3,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// ignore_for_file: deprecated_member_use_from_same_package
-part of '../firebase_core_platform_interface.dart';
+import 'package:collection/collection.dart';
+import 'package:meta/meta.dart';
 
 /// The options used to configure a Firebase app.
 ///
@@ -53,29 +53,6 @@ class FirebaseOptions {
     this.appGroupId,
   });
 
-  /// Named constructor to create [FirebaseOptions] from a the response of Pigeon channel.
-  ///
-  /// This constructor is used when platforms cannot directly return a
-  /// [FirebaseOptions] instance, for example when data is sent back from a
-  /// [MethodChannel].
-  FirebaseOptions.fromPigeon(CoreFirebaseOptions options)
-      : apiKey = options.apiKey,
-        appId = options.appId,
-        messagingSenderId = options.messagingSenderId,
-        projectId = options.projectId,
-        authDomain = options.authDomain,
-        databaseURL = options.databaseURL,
-        storageBucket = options.storageBucket,
-        measurementId = options.measurementId,
-        trackingId = options.trackingId,
-        deepLinkURLScheme = options.deepLinkURLScheme,
-        androidClientId = options.androidClientId,
-        iosClientId = options.iosClientId,
-        iosBundleId = options.iosBundleId,
-        appGroupId = options.appGroupId,
-        recaptchaSiteKey =
-            ''; // Placeholder to coordinate with fluttefire cli current operation.
-
   /// Returns a copy of this FirebaseOptions with the given fields replaced with
   /// the new values.
   FirebaseOptions copyWith({
diff --git a/packages/firebase_core/firebase_core_platform_interface/lib/src/platform_interface/platform_interface_firebase.dart b/packages/firebase_core/firebase_core_common/lib/src/platform_interface/platform_interface_firebase.dart
similarity index 50%
rename from packages/firebase_core/firebase_core_platform_interface/lib/src/platform_interface/platform_interface_firebase.dart
rename to packages/firebase_core/firebase_core_common/lib/src/platform_interface/platform_interface_firebase.dart
index 1129b5925a8d..a50d6548db5c 100644
--- a/packages/firebase_core/firebase_core_platform_interface/lib/src/platform_interface/platform_interface_firebase.dart
+++ b/packages/firebase_core/firebase_core_common/lib/src/platform_interface/platform_interface_firebase.dart
@@ -3,7 +3,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of '../../firebase_core_platform_interface.dart';
+import 'package:plugin_platform_interface/plugin_platform_interface.dart';
+
+import '../default_firebase_app_name.dart';
+import '../firebase_exception.dart';
+import '../firebase_options.dart';
+import 'platform_interface_firebase_app.dart';
 
 /// The interface that implementations of `firebase_core` must extend.
 ///
@@ -19,15 +24,43 @@ abstract class FirebasePlatform extends PlatformInterface {
 
   static final Object _token = Object();
 
+  /// Whether a [FirebasePlatform] implementation has been registered.
+  ///
+  /// Implementations register themselves by setting [FirebasePlatform.instance],
+  /// usually from their `registerWith` method which is called by the Flutter
+  /// plugin registrant (or manually when running outside of Flutter).
+  static bool get isRegistered => _instance != null;
+
   /// The default instance of [FirebasePlatform] to use.
   ///
-  /// Platform-specific plugins should override this with their own class
+  /// Platform-specific plugins should set this with their own class
   /// that extends [FirebasePlatform] when they register themselves.
   ///
-  /// Defaults to [MethodChannelFirebase].
-  static FirebasePlatform get instance => _instance;
+  /// Throws a [FirebaseException] if no implementation has been registered yet.
+  /// On Flutter, `firebase_core` registers its `MethodChannel` implementation
+  /// before the first usage of the `Firebase` API. Other platforms must call
+  /// the `registerWith` method of their implementation, for example
+  /// `FirebaseCoreWeb.registerWith(null)` on web.
+  static FirebasePlatform get instance {
+    final FirebasePlatform? instance = _instance;
+
+    if (instance == null) {
+      throw FirebaseException(
+        plugin: 'core',
+        code: 'no-platform-implementation',
+        message: 'No Firebase Core platform implementation has been '
+            'registered.\n\nIf you are using Flutter, this usually means that '
+            'the platform you are running on is not supported, or that '
+            '`Firebase.initializeApp()` has not been called yet.\n\nIf you are '
+            'not using Flutter, register your implementation manually, for '
+            'example by calling `FirebaseCoreWeb.registerWith(null)` on web.',
+      );
+    }
+
+    return instance;
+  }
 
-  static FirebasePlatform _instance = MethodChannelFirebase();
+  static FirebasePlatform? _instance;
 
   static set instance(FirebasePlatform instance) {
     PlatformInterface.verify(instance, _token);
diff --git a/packages/firebase_core/firebase_core_platform_interface/lib/src/platform_interface/platform_interface_firebase_app.dart b/packages/firebase_core/firebase_core_common/lib/src/platform_interface/platform_interface_firebase_app.dart
similarity index 92%
rename from packages/firebase_core/firebase_core_platform_interface/lib/src/platform_interface/platform_interface_firebase_app.dart
rename to packages/firebase_core/firebase_core_common/lib/src/platform_interface/platform_interface_firebase_app.dart
index 6fb7eb59baf6..98a9bd6879d0 100644
--- a/packages/firebase_core/firebase_core_platform_interface/lib/src/platform_interface/platform_interface_firebase_app.dart
+++ b/packages/firebase_core/firebase_core_common/lib/src/platform_interface/platform_interface_firebase_app.dart
@@ -3,7 +3,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of '../../firebase_core_platform_interface.dart';
+import 'package:plugin_platform_interface/plugin_platform_interface.dart';
+
+import '../default_firebase_app_name.dart';
+import '../firebase_options.dart';
 
 /// A class storing the name and options of a Firebase app.
 ///
@@ -26,7 +29,7 @@ class FirebaseAppPlatform extends PlatformInterface {
   final FirebaseOptions options;
 
   /// Returns whether this instance is the default Firebase app.
-  bool get _isDefault => name == defaultFirebaseAppName;
+  bool get isDefault => name == defaultFirebaseAppName;
 
   /// Returns true if automatic data collection is enabled for this app.
   bool get isAutomaticDataCollectionEnabled {
diff --git a/packages/firebase_core/firebase_core_platform_interface/lib/src/platform_interface/platform_interface_firebase_plugin.dart b/packages/firebase_core/firebase_core_common/lib/src/platform_interface/platform_interface_firebase_plugin.dart
similarity index 72%
rename from packages/firebase_core/firebase_core_platform_interface/lib/src/platform_interface/platform_interface_firebase_plugin.dart
rename to packages/firebase_core/firebase_core_common/lib/src/platform_interface/platform_interface_firebase_plugin.dart
index 42e470fdc1b6..6a39a41a4121 100644
--- a/packages/firebase_core/firebase_core_platform_interface/lib/src/platform_interface/platform_interface_firebase_plugin.dart
+++ b/packages/firebase_core/firebase_core_common/lib/src/platform_interface/platform_interface_firebase_plugin.dart
@@ -3,8 +3,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of '../../firebase_core_platform_interface.dart';
-
 /// The base class that other FlutterFire plugins must extend.
 ///
 /// This class provides access to common plugin properties and constants which
@@ -21,6 +19,24 @@ abstract class FirebasePlugin {
   /// requires that the value is synchronously available for use after initialization.
   static Map<dynamic, dynamic> _constantsForPluginApps = {};
 
+  /// Registers the plugin [constants] of [appName].
+  ///
+  /// Platform implementations call this once core has been initialized, so
+  /// that the constants are synchronously available to plugins afterwards.
+  static void registerConstantsForApp(
+    String appName,
+    Map<dynamic, dynamic>? constants,
+  ) {
+    if (constants != null) {
+      _constantsForPluginApps[appName] = constants;
+    }
+  }
+
+  /// Removes the constants registered for the plugins of [appName].
+  static void removeConstantsForApp(String appName) {
+    _constantsForPluginApps.remove(appName);
+  }
+
   final String _appName;
 
   final String _methodChannelName;
diff --git a/packages/firebase_core/firebase_core_common/pubspec.yaml b/packages/firebase_core/firebase_core_common/pubspec.yaml
new file mode 100644
index 000000000000..479b7b7ba3ac
--- /dev/null
+++ b/packages/firebase_core/firebase_core_common/pubspec.yaml
@@ -0,0 +1,21 @@
+name: firebase_core_common
+description: Pure Dart shared types and platform interfaces used by firebase_core
+  and its platform implementations.
+homepage: https://firebase.google.com/docs/flutter/setup
+repository: https://github.com/firebase/flutterfire/tree/main/packages/firebase_core/firebase_core_common
+version: 0.1.0
+resolution: workspace
+topics:
+  - firebase
+  - core
+
+environment:
+  sdk: '^3.6.0'
+
+dependencies:
+  collection: ^1.0.0
+  meta: ^1.8.0
+  plugin_platform_interface: ^2.1.3
+
+dev_dependencies:
+  test: ^1.25.0
diff --git a/packages/firebase_core/firebase_core_common/test/firebase_core_common_test.dart b/packages/firebase_core/firebase_core_common/test/firebase_core_common_test.dart
new file mode 100644
index 000000000000..77ecc0cf4e40
--- /dev/null
+++ b/packages/firebase_core/firebase_core_common/test/firebase_core_common_test.dart
@@ -0,0 +1,85 @@
+// Copyright 2026, the Chromium 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.
+
+import 'package:firebase_core_common/firebase_core_common.dart';
+import 'package:test/test.dart';
+
+const FirebaseOptions _options = FirebaseOptions(
+  apiKey: 'api-key',
+  appId: 'app-id',
+  messagingSenderId: 'sender-id',
+  projectId: 'project-id',
+);
+
+void main() {
+  group('$FirebasePlatform', () {
+    test('is not registered by default', () {
+      expect(FirebasePlatform.isRegistered, isFalse);
+    });
+
+    test('throws until an implementation is registered', () {
+      expect(
+        () => FirebasePlatform.instance,
+        throwsA(
+          isA<FirebaseException>().having(
+            (error) => error.code,
+            'code',
+            'no-platform-implementation',
+          ),
+        ),
+      );
+    });
+
+    test('can be set to a platform implementation', () {
+      FirebasePlatform.instance = _TestFirebasePlatform();
+
+      expect(FirebasePlatform.isRegistered, isTrue);
+      expect(FirebasePlatform.instance, isA<_TestFirebasePlatform>());
+    });
+  });
+
+  group('$FirebaseApp', () {
+    test('can be created from a platform delegate', () {
+      final FirebaseApp app = FirebaseApp.fromPlatform(_TestFirebaseApp());
+
+      expect(app.name, defaultFirebaseAppName);
+      expect(app.options, _options);
+      expect(app.toString(), contains(defaultFirebaseAppName));
+
+      // The delegate is verified when the app is created, so a platform
+      // implementation which does not extend `FirebaseAppPlatform` is rejected.
+      expect(
+        () => FirebaseApp.fromPlatform(_FakeFirebaseApp()),
+        throwsA(anything),
+      );
+    });
+  });
+
+  group('$FirebaseException', () {
+    test('exposes its plugin, code and message', () {
+      final FirebaseException exception = FirebaseException(
+        plugin: 'core',
+        code: 'no-app',
+        message: 'no app',
+      );
+
+      expect(exception.code, 'no-app');
+      expect(exception.toString(), contains('no app'));
+    });
+  });
+}
+
+class _TestFirebasePlatform extends FirebasePlatform {}
+
+class _TestFirebaseApp extends FirebaseAppPlatform {
+  _TestFirebaseApp() : super(defaultFirebaseAppName, _options);
+}
+
+// `FirebaseAppPlatform` overrides `==`, which is exactly why implementing it
+// (instead of extending it) is rejected when a [FirebaseApp] is created.
+// ignore: avoid_implementing_value_types
+class _FakeFirebaseApp implements FirebaseAppPlatform {
+  @override
+  dynamic noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+}
diff --git a/packages/firebase_core/firebase_core_platform_interface/lib/firebase_core_platform_interface.dart b/packages/firebase_core/firebase_core_platform_interface/lib/firebase_core_platform_interface.dart
index 5e5fe29248f1..8b5646598463 100644
--- a/packages/firebase_core/firebase_core_platform_interface/lib/firebase_core_platform_interface.dart
+++ b/packages/firebase_core/firebase_core_platform_interface/lib/firebase_core_platform_interface.dart
@@ -8,20 +8,17 @@ library;
 
 import 'dart:async';
 
-import 'package:collection/collection.dart';
+import 'package:firebase_core_common/firebase_core_common.dart';
 import 'package:firebase_core_platform_interface/src/pigeon/messages.pigeon.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
-import 'package:plugin_platform_interface/plugin_platform_interface.dart';
 
-part 'src/firebase_core_exceptions.dart';
-part 'src/firebase_exception.dart';
-part 'src/firebase_options.dart';
+/// The parts of the platform interface which do not depend on Flutter live in
+/// `firebase_core_common`, so that they can be consumed outside of Flutter.
+/// They are imported by this library (so that the parts below can use them)
+/// and re-exported, to keep this package the single entry point for Flutter
+/// users.
+export 'package:firebase_core_common/firebase_core_common.dart';
+
 part 'src/method_channel/method_channel_firebase.dart';
 part 'src/method_channel/method_channel_firebase_app.dart';
-part 'src/platform_interface/platform_interface_firebase.dart';
-part 'src/platform_interface/platform_interface_firebase_app.dart';
-part 'src/platform_interface/platform_interface_firebase_plugin.dart';
-
-/// The default Firebase application name.
-const String defaultFirebaseAppName = '[DEFAULT]';
diff --git a/packages/firebase_core/firebase_core_platform_interface/lib/src/method_channel/method_channel_firebase.dart b/packages/firebase_core/firebase_core_platform_interface/lib/src/method_channel/method_channel_firebase.dart
index ad3dff75c9de..3c6a53a5cb5e 100644
--- a/packages/firebase_core/firebase_core_platform_interface/lib/src/method_channel/method_channel_firebase.dart
+++ b/packages/firebase_core/firebase_core_platform_interface/lib/src/method_channel/method_channel_firebase.dart
@@ -38,15 +38,17 @@ class MethodChannelFirebase extends FirebasePlatform {
     MethodChannelFirebaseApp methodChannelFirebaseApp =
         MethodChannelFirebaseApp(
       response.name,
-      FirebaseOptions.fromPigeon(response.options),
+      firebaseOptionsFromPigeon(response.options),
       isAutomaticDataCollectionEnabled:
           response.isAutomaticDataCollectionEnabled,
     );
 
     appInstances[methodChannelFirebaseApp.name] = methodChannelFirebaseApp;
 
-    FirebasePlugin._constantsForPluginApps[methodChannelFirebaseApp.name] =
-        response.pluginConstants;
+    FirebasePlugin.registerConstantsForApp(
+      methodChannelFirebaseApp.name,
+      response.pluginConstants,
+    );
   }
 
   /// Returns the created [FirebaseAppPlatform] instances.
@@ -83,7 +85,7 @@ class MethodChannelFirebase extends FirebasePlatform {
           defaultApp == null &&
           _options == null) {
         final options = await api.optionsFromResource();
-        _options = FirebaseOptions.fromPigeon(options);
+        _options = firebaseOptionsFromPigeon(options);
       }
 
       // If no options are present & no default app has been setup, the user is
@@ -191,3 +193,30 @@ class MethodChannelFirebase extends FirebasePlatform {
     throw noAppExists(name);
   }
 }
+
+/// Creates a [FirebaseOptions] from the Pigeon representation used to send the
+/// options of a [FirebaseAppPlatform] across a [MethodChannel].
+///
+/// This replaces the `FirebaseOptions.fromPigeon` named constructor, which was
+/// removed so that [FirebaseOptions] (exposed by `firebase_core_common`) does
+/// not depend on the Flutter dependent Pigeon generated models.
+FirebaseOptions firebaseOptionsFromPigeon(CoreFirebaseOptions options) {
+  return FirebaseOptions(
+    apiKey: options.apiKey,
+    appId: options.appId,
+    messagingSenderId: options.messagingSenderId,
+    projectId: options.projectId,
+    authDomain: options.authDomain,
+    databaseURL: options.databaseURL,
+    storageBucket: options.storageBucket,
+    measurementId: options.measurementId,
+    trackingId: options.trackingId,
+    deepLinkURLScheme: options.deepLinkURLScheme,
+    androidClientId: options.androidClientId,
+    iosClientId: options.iosClientId,
+    iosBundleId: options.iosBundleId,
+    appGroupId: options.appGroupId,
+    // Placeholder to coordinate with the flutterfire CLI current operation.
+    recaptchaSiteKey: '',
+  );
+}
diff --git a/packages/firebase_core/firebase_core_platform_interface/lib/src/method_channel/method_channel_firebase_app.dart b/packages/firebase_core/firebase_core_platform_interface/lib/src/method_channel/method_channel_firebase_app.dart
index 4bfc28642b15..1683b299afa1 100644
--- a/packages/firebase_core/firebase_core_platform_interface/lib/src/method_channel/method_channel_firebase_app.dart
+++ b/packages/firebase_core/firebase_core_platform_interface/lib/src/method_channel/method_channel_firebase_app.dart
@@ -41,7 +41,7 @@ class MethodChannelFirebaseApp extends FirebaseAppPlatform {
   /// The default app cannot be deleted.
   @override
   Future<void> delete() async {
-    if (_isDefault) {
+    if (isDefault) {
       throw noDefaultAppDelete();
     }
 
@@ -52,7 +52,7 @@ class MethodChannelFirebaseApp extends FirebaseAppPlatform {
     await _api.delete(name);
 
     MethodChannelFirebase.appInstances.remove(name);
-    FirebasePlugin._constantsForPluginApps.remove(name);
+    FirebasePlugin.removeConstantsForApp(name);
     _isDeleted = true;
   }
 
diff --git a/packages/firebase_core/firebase_core_platform_interface/pubspec.yaml b/packages/firebase_core/firebase_core_platform_interface/pubspec.yaml
index d481587bd71a..85184605d73a 100644
--- a/packages/firebase_core/firebase_core_platform_interface/pubspec.yaml
+++ b/packages/firebase_core/firebase_core_platform_interface/pubspec.yaml
@@ -12,7 +12,7 @@ environment:
   flutter: '>=3.27.0'
 
 dependencies:
-  collection: ^1.0.0
+  firebase_core_common: ^0.1.0
   flutter:
     sdk: flutter
   meta: ^1.8.0
diff --git a/packages/firebase_core/firebase_core_platform_interface/test/firebase_options_test.dart b/packages/firebase_core/firebase_core_platform_interface/test/firebase_options_test.dart
index 8b84f78e9525..08ae84c564c5 100644
--- a/packages/firebase_core/firebase_core_platform_interface/test/firebase_options_test.dart
+++ b/packages/firebase_core/firebase_core_platform_interface/test/firebase_options_test.dart
@@ -48,8 +48,8 @@ void main() {
       expect(options1 == options2, isFalse);
     });
 
-    test('should construct an instance from a Map', () {
-      FirebaseOptions options1 = FirebaseOptions.fromPigeon(
+    test('should construct an instance from a Pigeon response', () {
+      FirebaseOptions options1 = firebaseOptionsFromPigeon(
         CoreFirebaseOptions(
           apiKey: 'apiKey',
           appId: 'appId',
diff --git a/packages/firebase_core/firebase_core_platform_interface/test/platform_interface_tests/platform_interface_firebase_core_test.dart b/packages/firebase_core/firebase_core_platform_interface/test/platform_interface_tests/platform_interface_firebase_core_test.dart
index 5393a22f99d8..7217d5d27d34 100644
--- a/packages/firebase_core/firebase_core_platform_interface/test/platform_interface_tests/platform_interface_firebase_core_test.dart
+++ b/packages/firebase_core/firebase_core_platform_interface/test/platform_interface_tests/platform_interface_firebase_core_test.dart
@@ -13,8 +13,12 @@ void main() {
 
   group('$FirebasePlatform', () {
     // should allow read of default app from native
-    test('$MethodChannelFirebase is the default instance', () {
+    test('$MethodChannelFirebase can be registered as the default instance',
+        () {
+      FirebasePlatform.instance = MethodChannelFirebase();
+
       expect(FirebasePlatform.instance, isA<MethodChannelFirebase>());
+      expect(FirebasePlatform.isRegistered, isTrue);
     });
 
     test('Can be extended', () {
diff --git a/packages/firebase_core/firebase_core_web/lib/firebase_core_web.dart b/packages/firebase_core/firebase_core_web/lib/firebase_core_web.dart
index ad0a67e97a2f..5e63bff15a7c 100644
--- a/packages/firebase_core/firebase_core_web/lib/firebase_core_web.dart
+++ b/packages/firebase_core/firebase_core_web/lib/firebase_core_web.dart
@@ -7,7 +7,7 @@ import 'dart:async';
 import 'dart:js_interop';
 import 'dart:js_interop_unsafe';
 
-import 'package:firebase_core_platform_interface/firebase_core_platform_interface.dart';
+import 'package:firebase_core_common/firebase_core_common.dart';
 import 'package:firebase_core_web/src/firebase_core_version.dart';
 import 'package:firebase_core_web/src/interop/package_web_tweaks.dart';
 import 'package:firebase_core_web/src/interop/utils/es6_interop.dart';
diff --git a/packages/firebase_core/firebase_core_web/lib/src/interop/core.dart b/packages/firebase_core/firebase_core_web/lib/src/interop/core.dart
index 3baa52ceb339..aaa9c556fa57 100644
--- a/packages/firebase_core/firebase_core_web/lib/src/interop/core.dart
+++ b/packages/firebase_core/firebase_core_web/lib/src/interop/core.dart
@@ -7,7 +7,7 @@
 
 import 'dart:js_interop';
 
-import 'package:firebase_core_platform_interface/firebase_core_platform_interface.dart';
+import 'package:firebase_core_common/firebase_core_common.dart';
 import 'package:firebase_core_web/firebase_core_web_interop.dart';
 
 import 'core_interop.dart' as firebase_interop;
diff --git a/packages/firebase_core/firebase_core_web/pubspec.yaml b/packages/firebase_core/firebase_core_web/pubspec.yaml
index 4264fabebd19..4bdf6e06d38f 100644
--- a/packages/firebase_core/firebase_core_web/pubspec.yaml
+++ b/packages/firebase_core/firebase_core_web/pubspec.yaml
@@ -7,10 +7,9 @@ resolution: workspace
 
 environment:
   sdk: '^3.6.0'
-  flutter: '>=3.22.0'
 
 dependencies:
-  firebase_core_platform_interface: ^8.1.1
+  firebase_core_common: ^0.1.0
   meta: ^1.8.0
   web: ^1.0.0
 
diff --git a/packages/firebase_core/firebase_core_web/test/firebase_core_web_app_check_multi_app_test.dart b/packages/firebase_core/firebase_core_web/test/firebase_core_web_app_check_multi_app_test.dart
index 88bfad5eb7a1..c66acb406b41 100644
--- a/packages/firebase_core/firebase_core_web/test/firebase_core_web_app_check_multi_app_test.dart
+++ b/packages/firebase_core/firebase_core_web/test/firebase_core_web_app_check_multi_app_test.dart
@@ -5,7 +5,7 @@
 @TestOn('browser')
 library;
 
-import 'package:firebase_core_platform_interface/firebase_core_platform_interface.dart';
+import 'package:firebase_core_common/firebase_core_common.dart';
 import 'package:firebase_core_web/firebase_core_web.dart';
 import 'package:flutter_test/flutter_test.dart';
 
diff --git a/packages/firebase_core/firebase_core_web/test/firebase_core_web_exceptions_test.dart b/packages/firebase_core/firebase_core_web/test/firebase_core_web_exceptions_test.dart
index ada205142773..c99f6cfa8d87 100644
--- a/packages/firebase_core/firebase_core_web/test/firebase_core_web_exceptions_test.dart
+++ b/packages/firebase_core/firebase_core_web/test/firebase_core_web_exceptions_test.dart
@@ -7,7 +7,7 @@
 import 'dart:js_interop';
 import 'dart:js_interop_unsafe';
 
-import 'package:firebase_core_platform_interface/firebase_core_platform_interface.dart';
+import 'package:firebase_core_common/firebase_core_common.dart';
 import 'package:firebase_core_web/firebase_core_web.dart';
 import 'package:flutter_test/flutter_test.dart';
 
diff --git a/packages/firebase_core/firebase_core_web/tool/pure_dart_check.dart b/packages/firebase_core/firebase_core_web/tool/pure_dart_check.dart
new file mode 100644
index 000000000000..3a84d197a53b
--- /dev/null
+++ b/packages/firebase_core/firebase_core_web/tool/pure_dart_check.dart
@@ -0,0 +1,24 @@
+// Copyright 2026, the Chromium 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.
+
+// A pure Dart entry point which verifies that this package can be used without
+// a Flutter dependency, which is the point of extracting
+// `firebase_core_common`.
+//
+// It is compiled by `melos run check:pure-dart`:
+// `dart compile js tool/pure_dart_check.dart` fails as soon as a library which
+// depends on Flutter becomes reachable from this package.
+import 'package:firebase_core_common/firebase_core_common.dart';
+import 'package:firebase_core_web/firebase_core_web.dart';
+
+void main() {
+  FirebaseCoreWeb.registerWith(null);
+
+  if (!FirebasePlatform.isRegistered) {
+    throw StateError('The web implementation did not register itself.');
+  }
+
+  // ignore: avoid_print
+  print('firebase_core_web is usable without Flutter.');
+}
diff --git a/pubspec.yaml b/pubspec.yaml
index e3d6f3195b02..105ac1a8958e 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -34,6 +34,7 @@ workspace:
   - packages/firebase_auth/firebase_auth_web
   - packages/firebase_core/firebase_core
   - packages/firebase_core/firebase_core/example
+  - packages/firebase_core/firebase_core_common
   - packages/firebase_core/firebase_core_platform_interface
   - packages/firebase_core/firebase_core_web
   - packages/firebase_crashlytics/firebase_crashlytics
@@ -503,6 +504,16 @@ melos:
     postclean: >
       melos exec -c 6 -- "flutter clean"
 
+    check:pure-dart:
+      run: |
+        melos exec --scope=firebase_core_web -- \
+          "dart compile js tool/pure_dart_check.dart --output=/tmp/flutterfire_pure_dart_core_check.js"
+      description: |-
+        Compile a pure Dart entry point which uses the web implementation of
+        firebase_core. It fails as soon as a library which depends on Flutter
+        becomes reachable, which is what allows the web implementation to be
+        used without Flutter, for example in pure Dart web applications.
+
     add-license-header:
       # If you add here another --ignore flag, add it also to
       # "check-license-header".