Flutter and Supabase Authentication Workflow

When building a mobile app, one of the most important (and sometimes scariest) parts is the login system. Fortunately, with Flutter and Supabase, setting up authentication becomes surprisingly easy and developer-friendly. In this article, we’ll explore the complete workflow of using Supabase Auth in a Flutter app  from project setup to actual login logic. Let’s go!

 

What is Supabase?

Supabase is an open-source Firebase alternative. It offers a real-time Postgres database, authentication, storage, and edge functions. In other words: everything you need to build an app backend without reinventing the wheel.

 

Why Use Supabase for Authentication?

•  Email/Password login out of the box
•  Magic link support
•  OAuth providers (Google, GitHub, etc.)
•  Secure, scalable, and open source
•  Works perfectly with Flutter using official SDK

 

Flutter + Supabase Auth Workflow Overview

Here’s the general flow of authentication using Flutter and Supabase:

1. Create a Supabase project
2. Install Flutter dependencies
3. Initialize Supabase client
4. Build login/register screens
5. Call Supabase Auth API
6. React to session changes (logged in or out)

 

Step 1: Create a Supabase Project

Go to supabase.com, create an account, and start a new project. You’ll get a project URL and anon key keep these safe, you'll use them in Flutter later.

 

Step 2: Install Flutter Dependencies

Add this to your pubspec.yaml:

dependencies:
  flutter:
    sdk: flutter
  supabase_flutter: ^1.10.17
  

 

Step 3: Initialize Supabase

In your main.dart file:

import 'package:flutter/material.dart';
import 'package:supabase_flutter/supabase_flutter.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Supabase.initialize(
    url: 'https://your-project.supabase.co',
    anonKey: 'your-anon-key',
  );
  runApp(MyApp());
}

 

Step 4: Create a Login and Register Screen

Here’s a basic example for login:

Future signIn(String email, String password) async {
  final response = await Supabase.instance.client.auth.signInWithPassword(
    email: email,
    password: password,
  );
  if (response.user != null) {
    print('Login success: ${response.user!.email}');
  } else {
    print('Login failed');
  }
}

And for registration:

Future signUp(String email, String password) async {
  final response = await Supabase.instance.client.auth.signUp(
    email: email,
    password: password,
  );
  if (response.user != null) {
    print('Registration successful');
  } else {
    print('Failed to register');
  }
}

 

Step 5: Handling Auth State

Use this widget to check whether a user is logged in or not:

Widget build(BuildContext context) {
  final session = Supabase.instance.client.auth.currentSession;
  if (session != null) {
    return HomeScreen();
  } else {
    return LoginScreen();
  }
}

 

Tips

•  Add magic link login via signInWithOtp
•  Use auth.onAuthStateChange for real-time state change
•  Secure routes based on auth state

 

Testing Your Flow

Test the login and register flow on both Android emulator and physical device. Supabase makes it easy to track users via their dashboard.

Flutter + Supabase is a powerful combo for building apps with authentication. The workflow is simple, clean, and scalable. You don’t need to manage tokens manually or worry about backend complexity  Supabase handles that for you.