Reference Authentication Flow with Flutter & Firebase

YouTube video walk-throughs here:

This project shows how to implement a full authentication flow in Flutter, using various Firebase sign-in methods.

It aims to be a reference implementation. Think of it as "authentication done right".

Project goals

This project shows how to:

use the various Firebase sign-in methods
build a robust authentication flow
use appropriate state management techniques to separate UI, logic and Firebase authentication code
handle errors and present user-friendly error messages
write production-ready code following best practices

Feel free to use this in your own projects. 😉

NOTE: This project will be kept up to date with the latest packages and Flutter version.

Preview

Google Sign-in

Facebook Sign-in

Email & Password auth

Simplified widget tree

FirebaseAuth features

Supported sign-in methods

Link account with third-party providers

Other authentication features

Email verification (for email & password sign-in)
Password reset
Sign-in with custom token

Application features

Sign-in Page

Navigation to email and password sign-in
Google sign-in
Facebook sign-in
Anonymous sign-in

Email & password page

Custom submit button with loading state
Disable all input widgets while authentication is in progress
Email regex validation
Error hints
Focus order (email -> password -> submit by pressing "next" on keyboard)
Password of at least 8 characters
Show/hide password
Password reset flow

Email link page

Email input field, backed by secure storage

Authentication

Abstract AuthService class, modeled after the firebase_auth API
FirebaseAuthService implementation
MockAuthService for testing
Firebase project configuration for iOS & Android
Toggle FirebaseAuthService and MockAuthService at runtime via developer menu

Architecture

Logic inside models for better separation of concerns (using ChangeNotifier)
Use Provider package for dependency injection

Other

Platform-aware alert dialogs for confirmation/error messages
Fully compliant with the official Flutter analysis_options.yaml rules

TODO

Internationalization
Full test coverage
Improve documentation

Running the project with Firebase

To use this project with Firebase authentication, some configuration steps are required.

Create a new project with the Firebase console.
Add iOS and Android apps in the Firebase project settings.
On Android, use com.codingwithflutter.firebase_auth_demo_flutter as the package name (a SHA-1 certificate fingerprint is also needed for Google sign-in).
then, download and copy google-services.json into android/app.
On iOS, use com.codingwithflutter.firebaseAuthDemo as the bundle ID.
then, download and copy GoogleService-Info.plist into iOS/Runner, and add it to the Runner target in Xcode.

See this document for full instructions:

https://firebase.google.com/docs/flutter/setup

Additional setup instructions for Google and Facebook sign-in:

Google Sign-In on iOS: https://firebase.google.com/docs/auth/ios/google-signin
Google Sign-In on Android: https://firebase.google.com/docs/auth/android/google-signin
Facebook Login for Android: https://developers.facebook.com/docs/facebook-login/android
Facebook Login for iOS: https://developers.facebook.com/docs/facebook-login/ios

Additional References

A lot of the techniques used in this project are explained in great detail, and implemented step-by-step in my Flutter & Firebase Udemy course.

This is available for early access at this link (discount code included):

Flutter & Firebase: Build a Complete App for iOS & Android

valtbarbos/firebase_auth_demo_flutter