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 GatewayAPI 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 GatewayAPI 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:

1. 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.
2. 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.
3. 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

tip:

• 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

npm i next-auth@beta

pnpm

pnpm add next-auth@beta

yarn

yarn add next-auth@beta

See Auth.js documentation for more details.

Set up Auth.js provider

tip:

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

Setup environment variables:

AUTH_LOGTO_ISSUER=https://xxxx.logto.app/oidc
AUTH_LOGTO_ID=your-logto-app-id
AUTH_LOGTO_SECRET=your-logto-app-secret

./app/api/auth/[...nextauth]/route.ts

import { handlers } from '@/auth';
export const { GET, POST } = handlers;

./auth.ts

import NextAuth from 'next-auth';
import Logto from 'next-auth/providers/logto';

export const { handlers, signIn, signOut, auth } = NextAuth({
  providers: [Logto],
});

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

./middleware.ts

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

Next Auth v4

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 };

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

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

Configure sign-in redirect URI

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:

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

Regarding redirect-based sign-in

1. This authentication process follows the OpenID Connect (OIDC) protocol, and Logto enforces strict security measures to protect user sign-in.
2. 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.

---

note:

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".

Implement sign-in and sign-out

Implement sign-in and sign-out button

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>
  );
}

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

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 GatewayAPI connector

SMS connector is a method used to send one-time passwords (OTPs) for authentication. It enables Phone number verification to support passwordless authentication, including SMS-based registration, sign-in, two-factor authentication (2FA), and account recovery. You can easily connect GatewayAPI as your SMS provider. With the Logto SMS connector, you can set this up in just a few minutes.

To add a SMS connector, simply follow these steps:

1. Navigate to Console > Connector > Email and SMS connectors.
2. To add a new SMS connector, click the "Set up" button and select "GatewayAPI".
3. Review the README documentation for your selected provider.
4. Complete the configuration fields in the "Parameter Configuration" section.
5. Customize the SMS template using the JSON editor.
6. Test your configuration by sending a verification code to your Phone number.

note:

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

Set up GatewayAPI SMS connector

Create an GatewayAPI account

Go to the GatewayAPI website and register your GatewayAPI account if you don't have one.

Enable account

You may need to enable your account before using the SMS service. You can contact the GatewayAPI customer service to enable your account.

Get API token

Go to the API Keys page from the GatewayAPI console, and find the API token or create a new API token.

Set up in Logto

1. Endpoint: If your GatewayAPI account is in the EU region, you should use the endpoint https://gatewayapi.com/rest/mtsms. If your GatewayAPI account is in the US region, you should use the endpoint https://gatewayapi.com/rest/mtsms.
2. API Token: The API token you created in the previous step.
3. Sender: The sender you want to use to send the SMS.
4. Templates: The templates you want to use to send the SMS, you can use the default templates or modify them as needed.

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 GatewayAPI connector should be available now.

Enable GatewayAPI connector in Sign-in Experience

Once you create a connector successfully, you can enable phone number-based passwordless login and registration.

1. Navigate to Console > Sign-in experience > Sign-up and sign-in.
2. Set up sign-up methods (Optional):
   1. Select "Phone number" or "Email or phone number" as the sign-up identifier.
   2. "Verify at sign-up" is forced to be enabled. You can also enable "Create a password" on registration.
3. Set up sign-in methods:
   1. Select Phone number as one of sign-in identifiers. You can provide multiple available identifiers (email, phone number, and username).
   2. Select "Verification code" and / or "Password" as the authentication factor.
4. Click "Save changes" and test it in "Live preview".

In addition to registration and login via OTPs, you can also have password recovery and -based security verification enabled, as well as linking Phone number to profile. See End-user flows for more details.

Testing and Validation

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

Further readings

End-user flows: Logto provides a out-of-the-box authentication flows including MFA and enterprise SSO, along with powerful APIs for flexible implementation of account settings, security verification, and multi-tenant experience.

Authorization: Authorization defines the actions a user can do or resources they can access after being authenticated. Explore how to protect your API for native and single-page applications and implement Role-based Access Control (RBAC).

Organizations: Particularly effective in multi-tenant SaaS and B2B apps, the organization feature enable tenant creation, member management, organization-level RBAC, and just-in-time-provisioning.

Customer IAM series Our serial blog posts about Customer (or Consumer) Identity and Access Management, from 101 to advanced topics and beyond.