How to build OAuth2 sign-in with Auth.js (Next Auth)

For our new friends:

Logto is an Auth0 alternative designed for modern apps and SaaS products. It offers both Cloud and Open-source services to help you quickly launch your identity and management (IAM) system. Enjoy authentication, authorization, and multi-tenant management all in one.

We recommend starting with a free development tenant on Logto Cloud. This allows you to explore all the features easily.

In this article, we will go through the steps to quickly build the OAuth2 sign-in experience (user authentication) with Auth.js (Next Auth) and Logto.

Prerequisites

A running Logto instance. Check out the introduction page to get started.
Basic knowledge of Auth.js (Next Auth).
A usable OAuth2 account.

Create an application in Logto

Logto is based on OpenID Connect (OIDC) authentication and OAuth 2.0 authorization. It supports federated identity management across multiple applications, commonly called Single Sign-On (SSO).

To create your Traditional web application, simply follow these steps:

Open the Logto Console. In the "Get started" section, click the "View all" link to open the application frameworks list. Alternatively, you can navigate to Logto Console > Applications, and click the "Create application" button.
In the opening modal, click the "Traditional web" section or filter all the available "Traditional web" frameworks using the quick filter checkboxes on the left. Click the "Auth.js (Next Auth)" framework card to start creating your application.
Enter the application name, e.g., "Bookstore," and click "Create application".

🎉 Ta-da! You just created your first application in Logto. You'll see a congrats page which includes a detailed integration guide. Follow the guide to see what the experience will be in your application.

Integrate Auth.js (Next Auth) with Logto

astuce:

In this guide, we assume you have set up Next Auth in your Next.js project. If you haven't, check out the Next Auth documentation to get started.

Installation

Install Auth.js via your favorite package manager:

npm
pnpm
yarn

npm i next-auth@beta

pnpm add next-auth@beta

yarn add next-auth@beta

See Auth.js documentation for more details.

Set up Auth.js provider

astuce:

You can find and copy "App Secret" from application details page in Admin Console:

Modify your API route config of Auth.js, add Logto as an OIDC provider:

Auth.js v5
Next Auth v4

./app/api/auth/[...nextauth]/route.ts
import { handlers } from '@/auth';
export const { GET, POST } = handlers;

./auth.ts
import NextAuth from 'next-auth';

export const { handlers, signIn, signOut, auth } = NextAuth({
  providers: [
    {
      id: 'logto',
      name: 'Logto',
      type: 'oidc',
      // You can get the issuer value from the Logto Application Details page,
      // in the field "Issuer endpoint"
      issuer: 'https://xxxx.logto.app/oidc',
      clientId: '<logto-app-id>',
      clientSecret: '<logto-app-secret>',
      authorization: {
        params: { scope: 'openid offline_access profile email' },
      },
      profile(profile) {
        // You can customize the user profile mapping here
        return {
          id: profile.sub,
          name: profile.name ?? profile.username,
          email: profile.email,
          image: profile.picture,
        };
      },
    },
  ],
});

Replace the issuer URL with your Logto application's "Issuer endpoint".
Replace the clientId and clientSecret with your Logto application's ID and secret.
Customize the profile function to map the user profile to the Next Auth user object, the default mapping is shown in the example.

Then you can also add an optional Middleware to keep the session alive:

./middleware.ts
export { auth as middleware } from '@/auth';

app/api/auth/[...nextauth]/route.ts
import NextAuth from 'next-auth';

const handler = NextAuth({
  providers: [
    {
      id: 'logto',
      name: 'Logto',
      type: 'oauth',
      // You can get the well-known URL from the Logto Application Details page,
      // in the field "OpenID Provider configuration endpoint"
      wellKnown: 'https://xxxx.logto.app/oidc/.well-known/openid-configuration',
      authorization: { params: { scope: 'openid offline_access profile email' } },
      clientId: '<logto-app-id>',
      clientSecret: '<logto-app-secret>',
      client: {
        id_token_signed_response_alg: 'ES384',
      },
      profile(profile) {
        // You can customize the user profile mapping here
        return {
          id: profile.sub,
          name: profile.name ?? profile.username,
          email: profile.email,
          image: profile.picture,
        };
      },
    },
  ],
});

export { handler as GET, handler as POST };

Replace the wellKnown URL with your Logto application's "OpenID Provider configuration endpoint".
Replace the clientId and clientSecret with your Logto application's ID and secret.
Customize the profile function to map the user profile to the Next Auth user object, the default mapping is shown in the example.
Remember to set the id_token_signed_response_alg to ES384.

You can find more details in the Auth.js documentation.

Before we dive into the details, here's a quick overview of the end-user experience. The sign-in process can be simplified as follows:

Your app invokes the sign-in method.
The user is redirected to the Logto sign-in page. For native apps, the system browser is opened.
The user signs in and is redirected back to your app (configured as the redirect URI).

This authentication process follows the OpenID Connect (OIDC) protocol, and Logto enforces strict security measures to protect user sign-in.
If you have multiple apps, you can use the same identity provider (Logto). Once the user signs in to one app, Logto will automatically complete the sign-in process when the user accesses another app.

To learn more about the rationale and benefits of redirect-based sign-in, see Logto sign-in experience explained.

remarque:

In the following code snippets, we assume your app is running on http://localhost:3000/.

Let's switch to the Application details page of Logto Console. Add a Redirect URI http://localhost:3000/api/auth/callback/logto and click "Save changes".

app/components/sign-in.tsx
import { signIn } from '@/auth';

export default function SignIn() {
  return (
    <form
      action={async () => {
        'use server';
        await signIn('logto');
      }}
    >
      <button type="submit">Sign In</button>
    </form>
  );
}

app/components/sign-out.tsx
import { signOut } from '@/auth';

export function SignOut() {
  return (
    <form
      action={async () => {
        'use server';
        await signOut();
      }}
    >
      <button type="submit">Sign Out</button>
    </form>
  );
}

app/page.tsx
import SignIn from './components/sign-in';
import SignOut from './components/sign-out';
import { auth } from '@/auth';

export default function Home() {
  const session = await auth();

  return <div>{session?.user ? <SignOut /> : <SignIn />}</div>;
}

Above is a simple example, you can check the Auth.js documentation for more details.

Checkpoint

Now, you can test your application to see if the authentication works as expected.

Add OAuth2 connector

To enable quick sign-in and improve user conversion, connect with Auth.js (Next Auth) as an identity provider. The Logto social connector helps you establish this connection in minutes by allowing several parameter inputs.

To add a social connector, simply follow these steps:

Navigate to Console > Connectors > Social Connectors.
Click "Add social connector" and select "OAuth2".
Follow the README guide and complete required fields and customize settings.

remarque:

If you are following the in-place Connector guide, you can skip the next section.

Set up Standard OAuth 2.0 app

Create your OAuth app

When you open this page, we believe you already know which social identity provider you want to connect to. The first thing to do is to confirm that the identity provider supports the OAuth protocol, which is a prerequisite for configuring a valid connector. Then, follow the identity provider's instructions to register and create the relevant app for OAuth authorization.

Configure your connector

We ONLY support "Authorization Code" grant type for security consideration and it can perfectly fit Logto's scenario.

clientId and clientSecret can be found at your OAuth apps details page.

clientId: The client ID is a unique identifier that identifies the client application during registration with the authorization server. This ID is used by the authorization server to verify the identity of the client application and to associate any authorized access tokens with that specific client application.

clientSecret: The client secret is a confidential key that is issued to the client application by the authorization server during registration. The client application uses this secret key to authenticate itself with the authorization server when requesting access tokens. The client secret is considered confidential information and should be kept secure at all times.

tokenEndpointAuthMethod: The token endpoint authentication method is used by the client application to authenticate itself with the authorization server when requesting access tokens. To discover supported methods, consult the token_endpoint_auth_methods_supported field available at the OAuth 2.0 service provider’s OpenID Connect discovery endpoint, or refer to the relevant documentation provided by the OAuth 2.0 service provider.

clientSecretJwtSigningAlgorithm (Optional): Only required when tokenEndpointAuthMethod is client_secret_jwt. The client secret JWT signing algorithm is used by the client application to sign the JWT that is sent to the authorization server during the token request.

scope: The scope parameter is used to specify the set of resources and permissions that the client application is requesting access to. The scope parameter is typically defined as a space-separated list of values that represent specific permissions. For example, a scope value of "read write" might indicate that the client application is requesting read and write access to a user's data.

You are expected to find authorizationEndpoint, tokenEndpoint and userInfoEndpoint in social vendor's documentation.

authenticationEndpoint: This endpoint is used to initiate the authentication process. The authentication process typically involves the user logging in and granting authorization for the client application to access their resources.

tokenEndpoint: This endpoint is used by the client application to obtain an access token that can be used to access the requested resources. The client application typically sends a request to the token endpoint with a grant type and authorization code to receive an access token.

userInfoEndpoint: This endpoint is used by the client application to obtain additional information about the user, such as their fullname, email address or profile picture. The user info endpoint is typically accessed after the client application has obtained an access token from the token endpoint.

Logto also provide a profileMap field that users can customize the mapping from the social vendors' profiles which are usually not standard. The keys are Logto's standard user profile field names and corresponding values should be social profiles' field names. In current stage, Logto only concern 'id', 'name', 'avatar', 'email' and 'phone' from social profile, only 'id' is required and others are optional fields.

responseType and grantType can ONLY be FIXED values with authorization code grant type, so we make them optional and default values will be automatically filled.

For example, you can find Google user profile response and hence its profileMap should be like:

{
  "id": "sub",
  "avatar": "picture"
}

remarque:

We provided an OPTIONAL customConfig key to put your customize parameters. Each social identity provider could have their own variant on OAuth standard protocol. If your desired social identity provider strictly stick to OAuth standard protocol, the you do not need to care about customConfig.

Config types

Name	Type	Required
authorizationEndpoint	string	true
userInfoEndpoint	string	true
clientId	string	true
clientSecret	string	true
tokenEndpointResponseType	enum	false
responseType	string	false
grantType	string	false
tokenEndpoint	string	false
scope	string	false
customConfig	Record<string, string>	false
profileMap	ProfileMap	false

ProfileMap fields	Type	Required	Default value
id	string	false	id
name	string	false	name
avatar	string	false	avatar
email	string	false	email
phone	string	false	phone

Save your configuration

Double check you have filled out necessary values in the Logto connector configuration area. Click "Save and Done" (or "Save changes") and the OAuth2 connector should be available now.

Once you create a social connector successfully, you can enable it as a "Continue with OAuth2" button in Sign-in Experience.

Navigate to Console > Sign-in experience > Sign-up and sign-in.
(Optional) Choose "Not applicable" for sign-up identifier if you need social login only.
Add configured OAuth2 connector to the "Social sign-in" section.

Testing and Validation

Return to your Auth.js (Next Auth) app. You should now be able to sign in with OAuth2. Enjoy!

Create an application in Logto​

Integrate Auth.js (Next Auth) with Logto​

Installation​

Set up Auth.js provider​

Configure sign-in redirect URI​

Regarding redirect-based sign-in​

Implement sign-in and sign-out​

Implement sign-in and sign-out button​

Show sign-in and sign-out button in the page​

Checkpoint​

Add OAuth2 connector​

Set up Standard OAuth 2.0 app​

Create your OAuth app​

Configure your connector​

Config types​

Save your configuration​

Enable OAuth2 connector in Sign-in Experience​

Testing and Validation​

Further readings​

Create an application in Logto

Integrate Auth.js (Next Auth) with Logto

Installation

Set up Auth.js provider

Configure sign-in redirect URI

Regarding redirect-based sign-in

Implement sign-in and sign-out

Implement sign-in and sign-out button

Show sign-in and sign-out button in the page

Checkpoint

Add OAuth2 connector

Set up Standard OAuth 2.0 app

Create your OAuth app

Configure your connector

Config types

Save your configuration

Enable OAuth2 connector in Sign-in Experience

Testing and Validation

Further readings