Add login to your Flutter app

Auth0 allows you to quickly add authentication and access user profile information in your application. This guide demonstrates how to integrate Auth0 with a Flutter application using the Auth0 Flutter SDK.

This quickstart assumes you already have a Flutter application up and running. If not, check out the Flutter "getting started" guides to get started with a simple app.

You should also be familiar with the Flutter command line tool.

Add the Auth0 Flutter SDK into the project:

flutter pub add auth0_flutter

If you are not developing for the Android platform, skip this step.

The SDK requires manifest placeholders. Auth0 uses placeholders internally to define an intent-filter, which captures the authentication callback URL. You must set the Auth0 tenant domain and the callback URL scheme.

Modify app/build.gradle to include manifest placeholders for auth0Domain and auth0Scheme inside the defaultConfig section:

apply plugin: 'com.android.application'

android {
    defaultConfig {
        applicationId "com.auth0.samples"
        minSdkVersion 21
        targetSdkVersion flutter.targetSdkVersion
        // ...

        // ---> Add the next line
        manifestPlaceholders += [auth0Domain: "{yourDomain}", auth0Scheme: "https"]
        // <---
    }
}

• auth0Domain: The domain of your Auth0 tenant. Generally, you find this in the Auth0 Dashboard under your Application's Settings in the Domain field. If you are using a custom domain, you should set this to the value of your custom domain instead.
• auth0Scheme: The scheme to use. Can be a custom scheme, or https if you want to use Android App Links. You can read more about setting this value in the Auth0.Android SDK README.

Run Sync Project with Gradle Files inside Android Studio to apply your changes.

If you are not developing for the iOS platform, skip this step.

You need to register your bundle identifier as a custom URL scheme so the callback and logout URLs can reach your app.

In Xcode, go to the Info tab of your app target settings. In the URL Types section, select the ＋ button to add a new entry. Then enter auth0 into the Identifier field and $(PRODUCT_BUNDLE_IDENTIFIER) into the URL Schemes field.

Universal Login is the easiest way to set up authentication in your application. We recommend using it for the best experience, best security, and the fullest array of features.

Integrate Auth0 Universal Login in your Flutter app by importing the SDK and instantiating the Auth0 class using your Auth0 domain and Client ID values. See this example, which instantiates the class inside a widget state object:

import 'package:auth0_flutter/auth0_flutter.dart';

class MainView extends StatefulWidget {
  const MainView({Key? key}) : super(key: key);

  @override
  State<MainView> createState() => _MainViewState();
}

class _MainViewState extends State<MainView> {
  Credentials? _credentials;

  late Auth0 auth0;

  @override
  void initState() {
    super.initState();
    auth0 = Auth0('{yourDomain}', '{yourClientId}');
  }

  @override
  Widget build(BuildContext context) {
    // ...
  }
}

Next, redirect your users to the Auth0 Universal Login page using webAuthentication().login(). This is a Future and must be awaited for you to retrieve the user's tokens. See this example of a ElevatedButton widget that logs the user in when clicked. Note that _credentials is used to determine locally within your app whether or not a user is signed in:

if (_credentials == null) {
  ElevatedButton(
    onPressed: () async {
      final credentials =
          await auth0.webAuthentication().login();

      setState(() {
        _credentials = credentials;
      });
    },
    child: const Text("Log in")
  )
}

Android: if you are using a custom scheme, pass this scheme to the login method so that the SDK can route to the login page and back again correctly:

await auth0.webAuthentication(scheme: 'YOUR CUSTOM SCHEME').login();

When a user logs in, they are redirected back to your application. Then, you are able to access the ID and access tokens for this user.

To log users out, redirect them to the Auth0 logout endpoint to clear their login session by calling the Auth0 Flutter SDK webAuthentication().logout(). Read more about logging out of Auth0.

See this example of an ElevatedButton widget that logs the user out of the app. Note that _credentials is set to null, indicating that the user is no longer signed in to your app:

ElevatedButton(
  onPressed: () async {
    await auth0.webAuthentication().logout();

    setState(() {
      _credentials = null;
    });
  },
  child: const Text("Log out"))

Android: if you are using a custom scheme, pass this scheme to the logout method so that the SDK can route back to your app correctly:

await auth0.webAuthentication(scheme: 'YOUR CUSTOM SCHEME').logout();

The user profile automatically retrieves user profile properties for you when you call webAuthentication().login(). The returned object from the login step contains a user property with all the user profile properties, which populates by decoding the ID token.

See this example of a View component that displays the user profile on the screen:

import 'package:auth0_flutter/auth0_flutter.dart';
import 'package:flutter/material.dart';

class ProfileView extends StatelessWidget {
  const ProfileView({Key? key, required this.user}) : super(key: key);

  final UserProfile user;

  @override
  Widget build(BuildContext context) {
    return Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: [
        if (user.name != null) Text(user.name!),
        if (user.email != null) Text(user.email!)
      ],
    );
  }
}