How to correctly set up Google Sign-In Redirect on Flutter Web?

[pinnakkkk]

I’m running into a limitation with Google Sign-In using popup on Flutter Web, which forces me to switch to redirect-based sign-in.

1. Why redirect?

Popups work, but the popup flow breaks in certain environments:

• Popup blockers
• Browsers that deny window.open
• Embedded webviews
• Browsers with strict cross-site policies

Because of that, I need Google Sign-In Redirect to work reliably.

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2. What I tried (simple minimal app)

Popup version works. Redirect version always returns null user after redirect.

Code (Redirect Flow Attempt)

Future<void> _signInWithGoogleRedirect() async {
  final provider = GoogleAuthProvider();
  provider.addScope('email');
  provider.addScope('profile');
  await FirebaseAuth.instance.signInWithRedirect(provider);
}

Future<void> _handleRedirectResult() async {
  final result = await FirebaseAuth.instance.getRedirectResult();
  print("Redirect result: ${result.user}"); // always null
}

Called in:

@override
void initState() {
  super.initState();
  _handleRedirectResult();
}

The rest of the minimal app uses a simple StreamBuilder<AuthState> to show UI.

another example: https://pastebin.com/wEKsyXH4

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3. Environment

Flutter Doctor

❯ flutter doctor
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.38.3, on macOS 26.1 25B78 darwin-arm64, locale en-US)
[✓] Android toolchain - develop for Android devices (Android SDK version 35.0.0)
[✓] Xcode - develop for iOS and macOS (Xcode 26.0.1)
[✓] Chrome - develop for the web
[✓] Connected device (3 available)
[✓] Network resources

• No issues found!

Firebase packages

# Firebase
  firebase_auth: ^6.1.2
  firebase_core: ^4.2.1
  google_sign_in: ^7.2.0
  google_sign_in_web: ^1.1.0

Web setup

• Firebase Hosting + localdev on localhost
• Correct Web Client ID
• <meta name="google-signin-client_id"> added
• Redirect URI is the default:
  https://<project>.firebaseapp.com/__/auth/handler
• All domains authorized

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4. The issue

The redirect completes successfully, but:

FirebaseAuth.instance.getRedirectResult()

always returns:

user = null
credential = null

Popup mode (signInWithPopup) works perfectly in the same app.