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 SAML enterprise SSO 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 SAML enterprise SSO 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

ヒント:

• 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

ヒント:

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

./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,
        };
      },
    },
  ],
});

1. Replace the issuer URL with your Logto application's "Issuer 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.

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.

---

注記:

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 SAML enterprise SSO connector

To simplify access management and gain enterprise-level safeguards for your big clients, connect with Auth.js (Next Auth) as a federated identity provider. The Logto enterprise SSO connector helps you establish this connection in minutes by allowing several parameter inputs.

To add an enterprise SSO connector, simply follow these steps:

1. Navigate to Logto console > Enterprise SSO.

2. Click "Add enterprise connector" button and choose your SSO provider type. Choose from prebuilt connectors for Microsoft Entra ID (Azure AD), Google Workspace, and Okta, or create a custom SSO connection using the standard OpenID Connect (OIDC) or SAML protocol.
3. Provide a unique name (e.g., SSO sign-in for Acme Company).

4. Configure the connection with your IdP in the "Connection" tab. Check the guides above for each connector types.

5. Customize the SSO experience and enterprise’s email domain in the "Experience" tab. Users sign in with the SSO-enabled email domain will be redirected to SSO authentication.

6. Save changes.

Set up SAML SSO application on your IdP

Step 1: Create a SAML SSO application on your IdP {#step-1-create-a-saml-sso-application-on-your-idp}

Initiate the SAML SSO integration by creating an application on the IdP side. Obtain the following configurations from Logto, representing your Service Provider (SP):

• Audience URI(SP Entity ID): It represents as a globally unique identifier for your Logto service, functioning as the EntityId for SP during authentication requests to the IdP. This identifier is pivotal for the secure exchange of SAML assertions and other authentication-related data between the IdP and Logto.
• ACS URL: The Assertion Consumer Service (ACS) URL is the location where the SAML assertion is sent with a POST request. This URL is used by the IdP to send the SAML assertion to Logto. It acts as a callback URL where Logto expects to receive and consume the SAML response containing the user's identity information.

Fill in the Audience URI and ACS URL configurations in your IdP SAML application and continue to retrieve the following configurations from your IdP.

Step 2: Configure SAML SSO on Logto

To make the SAML SSO integration work, you will need to provide the IdP metadata to Logto. The IdP metadata is an XML document that contains all the information required for Logto to establish the trust with the IdP.

Navigate to the Connection tab. Logto provides three different ways to configure the IdP metadata:

1. Metadata URL: Provide the URL of the IdP metadata XML document. Logto will fetch the metadata from the URL and configure the SAML SSO integration automatically.
2. Upload Metadata: Upload the IdP metadata XML document. Logto will parse the XML document and configure the SAML SSO integration automatically.
3. Manual Configuration: Manually configure the IdP metadata.

• IdP entity ID: The Entity ID of the IdP.
• Single sign-on URL: The URL of the IdP Single Sign-On Service.
• Signing certificate: The x509 certificate is used to verify the signature of the SAML response from the IdP.

With either of the above configurations, Logto will parse the IdP metadata and configure the SAML SSO integration accordingly.

Step 3: Configure user attributes mapping

The user attributes returned from IdP may vary depending on the IdP configuration. Logto provides a flexible way to map the user attributes returned from IdP to the user attributes in Logto. You can configure the user attributes mapping in the SAML SSO integration experience tab.

• id: The unique identifier of the user. Logto will read the nameId claim from the SAML response as the user SSO identity id.
• email: The email address of the user.
• name: The name of the user.

Step4: Set email domains and enable the SSO connector

Provide the email domains of your organization in Logto’s connector SSO experience tab. This will enable the SSO connector as an authentication method for those users.

Users with email addresses in the specified domains will be redirected to use the SAML SSO connector as their only authentication method.

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 SAML enterprise SSO connector should be available now.

Enable SAML enterprise SSO connector in Sign-in Experience

You don’t need to configure enterprise connectors individually, Logto simplifies SSO integration into your applications with just one click.

1. Navigate to: Console > Sign-in experience > Sign-up and sign-in.
2. Enable the "Enterprise SSO" toggle.
3. Save changes.

Once enabled, a "Single Sign-On" button will appear on your sign-in page. Enterprise users with SSO-enabled email domains can access your services using their enterprise identity providers (IdPs).

To learn more about the SSO user experience, including SP-initiated SSO and IdP-initiated SSO, refer to User flows: Enterprise SSO.

Testing and Validation

Return to your Auth.js (Next Auth) app. You should now be able to sign in with SAML enterprise SSO. 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.