Godot Google Sign-In Plugin

A native Android plugin for Godot 4.2+ that enables Google Sign-In using the modern Credential Manager API.

Features

• ✅ Native Google Sign-In on Android
• ✅ Uses modern Credential Manager API (Google's recommended approach)
• ✅ Returns ID token for Firebase Authentication
• ✅ Supports Godot 4.2+ (v2 plugin architecture)
• ✅ Auto-select previously signed-in accounts
• ✅ Account chooser support

Requirements

• Godot 4.2 or higher
• Android export with Gradle build enabled
• Google Cloud Console project with OAuth 2.0 credentials

Installation

Option 1: Pre-built Plugin (Recommended)

1. Copy the addons/GodotGoogleSignIn folder to your project's addons/ directory
2. In Godot, go to Project → Project Settings → Plugins
3. Enable GodotGoogleSignIn
4. Go to Project → Install Android Build Template...
5. In Export settings, enable Use Gradle Build

Option 2: Build from Source

See Building from Source below.

Setup

1. Google Cloud Console Setup

1. Go to Google Cloud Console
2. Create or select a project
3. Go to APIs & Services → Credentials
4. Create an OAuth 2.0 Client ID:
   • For Android: Select "Android" application type
   • Package name: Your app's package name (e.g., com.yourcompany.yourgame)
   • SHA-1 fingerprint: Your signing key's SHA-1
5. Create a Web Client ID (required for Firebase):
   • Select "Web application" type
   • This ID is used to get the ID token

2. Get Your SHA-1 Fingerprint

# Debug keystore
keytool -list -v -keystore ~/.android/debug.keystore -alias androiddebugkey -storepass android -keypass android

# Release keystore
keytool -list -v -keystore your-release-key.keystore -alias your-alias

Usage

extends Node

var google_sign_in: Object = null

func _ready():
    if OS.get_name() == "Android" and Engine.has_singleton("GodotGoogleSignIn"):
        google_sign_in = Engine.get_singleton("GodotGoogleSignIn")
        google_sign_in.connect("sign_in_success", _on_sign_in_success)
        google_sign_in.connect("sign_in_failed", _on_sign_in_failed)
        google_sign_in.connect("sign_out_complete", _on_sign_out_complete)
        
        # Initialize with your Web Client ID
        google_sign_in.initialize("YOUR_WEB_CLIENT_ID.apps.googleusercontent.com")

func sign_in():
    if google_sign_in:
        google_sign_in.signIn()  # Auto-selects if previously signed in
        # Or use: google_sign_in.signInWithGoogleButton()  # Always shows account picker

func sign_out():
    if google_sign_in:
        google_sign_in.signOut()

func _on_sign_in_success(id_token: String, email: String, display_name: String):
    print("Signed in as: ", email)
    print("Display name: ", display_name)
    # Use id_token with Firebase Auth:
    # https://identitytoolkit.googleapis.com/v1/accounts:signInWithIdp

func _on_sign_in_failed(error: String):
    print("Sign-in failed: ", error)

func _on_sign_out_complete():
    print("Signed out")

API Reference

Methods

Signals

Firebase Authentication

To authenticate with Firebase using the ID token:

func _sign_in_with_firebase(google_id_token: String):
    var url = "https://identitytoolkit.googleapis.com/v1/accounts:signInWithIdp?key=YOUR_FIREBASE_API_KEY"
    
    var body = {
        "postBody": "id_token=%s&providerId=google.com" % google_id_token,
        "requestUri": "http://localhost",
        "returnIdpCredential": true,
        "returnSecureToken": true
    }
    
    var http = HTTPRequest.new()
    add_child(http)
    http.request(url, ["Content-Type: application/json"], HTTPClient.METHOD_POST, JSON.stringify(body))

Building from Source

Requirements

• Android SDK (API 33+)
• Java 17+
• Gradle 8.4+

Build Steps

1. Clone this repository
2. Navigate to plugin/
3. Update local.properties with your Android SDK path:

   sdk.dir=C\:\\Users\\YourName\\AppData\\Local\\Android\\Sdk
   

4. Build:

   ./gradlew assembleRelease
   

5. The AAR will be in build/outputs/aar/

Dependencies

The plugin uses these Android libraries (automatically included via Gradle):

• androidx.credentials:credentials:1.3.0
• androidx.credentials:credentials-play-services-auth:1.3.0
• com.google.android.libraries.identity.googleid:googleid:1.1.1
• org.jetbrains.kotlinx:kotlinx-coroutines-android:1.7.3

Troubleshooting

"Plugin not available" error

• Make sure Use Gradle Build is enabled in Android export settings
• Install Android Build Template via Project → Install Android Build Template
• Ensure the plugin is enabled in Project Settings → Plugins

Sign-in cancelled immediately

• Verify your SHA-1 fingerprint matches in Google Cloud Console
• Check that package name matches exactly
• Ensure Web Client ID is correct

"No credentials available"

• The device needs at least one Google account signed in
• Play Services must be up to date

License

MIT License - see LICENSE

Credits

Built for Godot 4.5.1 using the v2 Android plugin architecture.

Uses Google's Credential Manager API for modern, secure authentication.