supabase_flutter_web_auth #

Runs supabase_flutter's signInWithOAuth, signInWithSSO, and linkIdentity flows through a system web authentication session (ASWebAuthenticationSession on iOS/macOS, Custom Tabs on Android) instead of a plain browser launch. On Linux and Windows there is no equivalent OS session, so the flow runs in an embedded webview window instead (see Setup below).

By default, supabase_flutter opens the sign-in URL with url_launcher. That browser surface does not close itself when the OAuth redirect returns to the app, so the user is left on a blank page after a successful sign-in and has to dismiss it manually. This package's launcher always auto-dismisses once the redirect arrives. On iOS/macOS and Android it also shares cookies with the system browser, so a user already signed in to a provider elsewhere isn't asked to sign in again; the embedded webview used on Linux and Windows has its own separate cookie store and does not share that session.

This behavior isn't the default in supabase_flutter because achieving it pulls in flutter_web_auth_2 and, on Linux/Windows, its own embedded-webview dependency. Add this package only if you want that trade-off.

Usage #

import 'package:supabase_flutter/supabase_flutter.dart';
import 'package:supabase_flutter_web_auth/supabase_flutter_web_auth.dart';

await Supabase.initialize(
  url: 'https://your-project.supabase.co',
  publishableKey: 'your-publishable-key',
  authOptions: const FlutterAuthClientOptions(
    oauthLauncher: FlutterWebAuth2OAuthLauncher(),
  ),
);

signInWithOAuth, signInWithSSO, and linkIdentity are called exactly as documented in supabase_flutter; the new preferEphemeral parameter (ignored by the default launcher) requests a session that does not share cookies with the system browser.

Setup #

Android #

Register the flutter_web_auth_2 callback activity for your redirect scheme in android/app/src/main/AndroidManifest.xml:

<activity
    android:name="com.linusu.flutter_web_auth_2.CallbackActivity"
    android:exported="true">
  <intent-filter android:label="flutter_web_auth_2">
    <action android:name="android.intent.action.VIEW" />
    <category android:name="android.intent.category.DEFAULT" />
    <category android:name="android.intent.category.BROWSABLE" />
    <data android:scheme="my-scheme" />
  </intent-filter>
</activity>

Replace my-scheme with the scheme of the redirectTo URL you pass to signInWithOAuth/signInWithSSO/linkIdentity.

iOS and macOS #

No extra configuration is needed for a custom URL scheme redirect. For an https universal link redirectTo, set up associated domains as usual.

Linux and Windows #

No native configuration is needed; the flow runs in an embedded webview window provided by flutter_web_auth_2.