expo-plugin-google-signin

An Expo config plugin that adds native Google Sign-In to Android using the modern Credential Manager API. Includes automatic nonce generation for secure Auth0 token exchange.

Why This Plugin?

• Modern API: Uses Android's Credential Manager instead of the deprecated Google Sign-In SDK
• One-Tap Experience: Native bottom sheet UI that users trust
• Auth0 Ready: Automatic nonce generation enables secure token exchange flows
• Zero Config: Works with Expo's managed workflow via config plugins

Installation

npm install expo-plugin-google-signin
# or
yarn add expo-plugin-google-signin

Setup

1. Add the Plugin

Add to your app.json or app.config.js:

{
  "expo": {
    "plugins": [
      ["expo-plugin-google-signin", {
        "androidPackage": "com.yourcompany.yourapp"
      }]
    ]
  }
}

Note: If androidPackage is not provided, it defaults to your app's android.package from Expo config.

2. Get a Web Client ID

You need a Web Client ID from Google Cloud Console (not Android Client ID):

1. Go to Google Cloud Console
2. Create or select a project
3. Create an OAuth 2.0 Client ID of type Web application
4. Copy the Client ID (ends with .apps.googleusercontent.com)

See docs/GOOGLE_CLOUD_SETUP.md for detailed instructions.

3. Rebuild Your App

npx expo prebuild --clean
npx expo run:android

Usage

import { signInWithGoogle, isGoogleSignInAvailable } from 'expo-plugin-google-signin';

const WEB_CLIENT_ID = 'your-web-client-id.apps.googleusercontent.com';

async function handleGoogleSignIn() {
  if (!isGoogleSignInAvailable()) {
    console.log('Google Sign-In not available on this platform');
    return;
  }

  try {
    const result = await signInWithGoogle(WEB_CLIENT_ID);
    
    if (result) {
      console.log('Signed in as:', result.displayName);
      console.log('Email:', result.id);
      console.log('ID Token:', result.idToken);
      
      // Use result.idToken for your backend or Auth0
    } else {
      console.log('User cancelled sign-in');
    }
  } catch (error) {
    console.error('Sign-in error:', error.code, error.message);
  }
}

API Reference

signInWithGoogle(webClientId: string): Promise<GoogleSignInResult | null>

Initiates the Google Sign-In flow using Credential Manager.

Parameters:

• webClientId - Your Web Client ID from Google Cloud Console

Returns:

• GoogleSignInResult on success
• null if user cancelled
• Throws on error

isGoogleSignInAvailable(): boolean

Check if Google Sign-In is available on the current platform.

Returns: true on Android with the native module loaded, false otherwise.

GoogleSignInResult

interface GoogleSignInResult {
  idToken: string;           // JWT token with nonce (use for Auth0/backend)
  id: string;                // User's email address
  displayName: string | null;
  givenName: string | null;
  familyName: string | null;
  profilePictureUri: string | null;
}

Error Codes

| Code | Description | |------|-------------| | SIGN_IN_CANCELLED | User cancelled the sign-in flow | | NO_CREDENTIAL | No Google account available on device | | CREDENTIAL_ERROR | Credential Manager error | | NO_ACTIVITY | App not in foreground |

Auth0 Integration

This plugin is designed to work with Auth0's Native Social Login feature. The ID token includes a nonce that Auth0 requires for secure token exchange.

import { signInWithGoogle } from 'expo-plugin-google-signin';

async function signInWithAuth0() {
  const googleResult = await signInWithGoogle(WEB_CLIENT_ID);
  if (!googleResult) return;

  // Exchange Google token for Auth0 token
  const response = await fetch(`https://${AUTH0_DOMAIN}/oauth/token`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      grant_type: 'urn:ietf:params:oauth:grant-type:token-exchange',
      subject_token: googleResult.idToken,
      subject_token_type: 'urn:ietf:params:oauth:token-type:id_token',
      client_id: AUTH0_CLIENT_ID,
      audience: AUTH0_AUDIENCE,
      scope: 'openid profile email',
    }),
  });

  const auth0Token = await response.json();
  // Use auth0Token.access_token for your API calls
}

See docs/AUTH0_INTEGRATION.md for complete setup instructions.

iOS Support

This plugin is Android only. For iOS, use expo-apple-authentication for native Sign in with Apple, then exchange the Apple token with Auth0 similarly.

import { isGoogleSignInAvailable } from 'expo-plugin-google-signin';
import * as AppleAuthentication from 'expo-apple-authentication';
import { Platform } from 'react-native';

async function handleNativeSignIn() {
  if (Platform.OS === 'android' && isGoogleSignInAvailable()) {
    return signInWithGoogle(WEB_CLIENT_ID);
  } else if (Platform.OS === 'ios') {
    return AppleAuthentication.signInAsync({
      requestedScopes: [
        AppleAuthentication.AppleAuthenticationScope.FULL_NAME,
        AppleAuthentication.AppleAuthenticationScope.EMAIL,
      ],
    });
  }
}

Troubleshooting

See docs/TROUBLESHOOTING.md for common issues and solutions.

Example

Check out the example directory for a complete working app.

Contributing

Contributions are welcome! Please read CONTRIBUTING.md first.

Publishing

See PUBLISHING.md for how to release new versions.

License

MIT