React: Login

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React: Login

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By Andres Aguiar

This tutorial demonstrates how to add user login to a React application using Auth0. We recommend you to Log in to follow this quickstart with examples configured for your account.

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2 minutes

Get a sample configured with your account settings or check it out on Github.

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System requirements: React 15.6

New to Auth? Learn How Auth0 works, how it integrates with Single-Page Applications and which protocol it uses.

Configure Auth0

Get Your Application Keys

When you signed up for Auth0, a new application was created for you, or you could have created a new one.

You will need some details about that application to communicate with Auth0. You can get these details from the Application Settings section in the Auth0 dashboard.

You need the following information:

  • Client ID
  • Domain

If you download the sample from the top of this page these details are filled out for you.

If you have more than one application in your account, the sample comes with the values for your Default App.

App Dashboard

Configure Callback URLs

A callback URL is a URL in your application where Auth0 redirects the user after they have authenticated.

You need to whitelist the callback URL for your app in the Allowed Callback URLs field in your Application Settings. If you do not set any callback URL, your users will see a mismatch error when they log in.

If you are following along with the sample project you downloaded from the top of this page, you should set the Allowed Callback URL to http://localhost:3000/callback.

Configure Logout URLs

A logout URL is a URL in your application that Auth0 can return to after the user has been logged out of the authorization server. This is specified in the returnTo query parameter.

You can set the logout URL for your app in the Allowed Logout URLs field in your Application Settings. If you don't set a logout URL, your users will be unable to log out of the application and will get an error.

Configure Allowed Web Origins

You need to whitelist the URL for your app in the Allowed Web Origins field in your Application Settings. If you don't whitelist your application URL, the application will be unable to automatically refresh the authentication tokens and your users will be logged out the next time they visit the application, or refresh the page.

Integrate Auth0 in your Application

Loading auth0.js

You need the auth0.js library to integrate Auth0 into your application. You can either install the library locally in your application or load it from CDN.

Loading via dependencies

Install auth0.js using npm or yarn.

Once you install auth0.js, add it to your build system or bring it in to your project with a script tag.

Loading it from CDN

If you do not want to use a package manager, you can retrieve auth0.js from Auth0's CDN.

Authentication with Auth0

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. This guide will use it to provide a way for your users to log in to your React application.

You can also embed the login dialog directly in your application using the Lock widget. If you use this method, some features, such as single sign-on, will not be accessible. To learn how to embed the Lock widget in your application, follow the Embedded Login sample.

When a user logs in, Auth0 returns three items:

You can use these items in your application to set up and manage authentication.

Create an Authentication Service

Create a service to manage and coordinate user authentication. You can give the service any name. In the examples below, the service is Auth and the filename is Auth.js.

In the service add an instance of the auth0.WebAuth object. When creating that instance, you can specify the following:

  • Configuration for your application and domain
  • Response type, to show that you need a user's Access Token and an ID Token after authentication
  • Audience and scope, specifying that you need an access_token that can be used to invoke the /userinfo endpoint.
  • The URL where you want to redirect your users after authentication.

In this tutorial, the route is /callback, which is implemented in the Add a Callback Component step.

Add a login method that calls the authorize method from auth0.js.


Try to import the Auth service from somewhere in your application. Call the login method from the service to see the login page. For example:

hosted login

Handle Authentication Tokens

Add more methods to the Auth service to handle authentication in the app.

The example below shows the following methods:

  • handleAuthentication: looks for the result of authentication in the URL hash. Then, the result is processed with the parseHash method from auth0.js
  • setSession: sets the user's Access Token, ID Token, and the Access Token's expiry time
  • logout: removes the user's tokens and expiry time from browser storage
  • isAuthenticated: checks whether the expiry time for the user's Access Token has passed

Provide a Login Control

Provide a component with controls for the user to log in and log out.

This example uses Bootstrap styles. You can use any style library you want, or not use one at all.

Depending on whether the user is authenticated or not, they see the Log In or Log Out button. The click events on the buttons make calls to the Auth service to let the user log out or log in. When the user clicks the Log In button, they are redirected to the login page.

The login page uses the Lock widget. To learn more about Universal Login and the login page, see the Universal Login documentation. To customize the look and feel of the Lock widget, see the Lock customization options documentation.

Add a Callback Component

When you use the login page, your users are taken away from your application. After they authenticate, the users automatically return to your application and a client-side session is set for them.

This example assumes you are using path-based routing with <BrowserRouter>. If you are using hash-based routing, you will not be able to specify a dedicated callback route. The URL hash will be used to hold the user's authentication information.

You can select any URL in your application for your users to return to. We recommend creating a dedicated callback route. If you create a single callback route:

  • You don't have to whitelist many, sometimes unknown, callback URLs.
  • You can display a loading indicator while the application sets up a client-side session.

Create a component named CallbackComponent and add a loading indicator.

To display a loading indicator, you need a loading spinner or another indicator in the assets directory. See the downloadable sample for demonstration.

After authentication, your users are taken to the /callback route. They see the loading indicator while the application sets up a client-side session for them. After the session is set up, the users are redirected to the /home route.

Process the Authentication Result

When a user authenticates at the login page, they are redirected to your application. Their URL contains a hash fragment with their authentication information. The handleAuthentication method in the Auth service processes the hash.

Call the handleAuthentication method after you render the Callback route. The method processes the authentication hash fragment when the Callback component initializes.

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