Google & Apple Sign-In in Flutter

A production-grade walkthrough: clean auth service, real code from a real app, and integration patterns. Table of Contents Introduction Prerequisites Dependencies & Setup Getting the Server Client ID The Clean AuthService Platform Configuration Common Errors & Fixes UI Example Conclusion 01 / Introduction Why Social Sign-In Still Matters in 2026 Every additional step between a user opening your app and them being inside it is a drop-off point. Password flows are friction. Google and Appl