Google Sign-In

Enable provider in Firebase

1. In Firebase Console → Authentication → Sign-in method, enable Google and select a support email.

Add SHA-1 fingerprint (Android)

Google Sign-In on Android requires SHA-1 (+ SHA-256) fingerprints for your keystore.

1. Generate for your build:

   cd android && ./gradlew signingReport
   

   For production, also copy SHA-1 from Google Play Console → Release → Setup → App signing.

2. In Firebase Console → Project Settings → General → your Android app → Add fingerprint, paste SHA-1 (and SHA-256 if available) and save.

3. Re-download google-services.json and replace android/app/google-services.json.

iOS URL scheme

1. Open your downloaded GoogleService-Info.plist, find <key>REVERSED_CLIENT_ID</key> and copy its <string> value (e.g. com.googleusercontent.apps.1234567890-abcdefg).

2. Ensure it appears in ios/Runner/Info.plist under CFBundleURLTypes:

<key>CFBundleURLTypes</key>
<array>
  <dict>
    <key>CFBundleTypeRole</key>
    <string>Editor</string>
    <key>CFBundleURLSchemes</key>
    <array>
      <string>YOUR_REVERSED_CLIENT_ID</string>
    </array>
  </dict>
  <!-- Keep prohandy-provider scheme in a separate dict — see Deep Linking -->
</array>

Test

Build and test Google Sign-In. DEVELOPER_ERROR usually means package name / SHA-1 / google-services.json mismatch.