SAML SSO with Okta

This guide walks you through setting up SAML Single Sign-On (SSO) with your Identity Provider (IdP), using Okta as an example. For advanced configuration details and the full API reference, check out the SSO Plugin Documentation.

What is SAML?

SAML (Security Assertion Markup Language) is an XML-based standard for exchanging authentication and authorization data between an Identity Provider (IdP) (e.g., Okta, Azure AD, OneLogin) and a Service Provider (SP) (in this case, Better Auth).

In this setup:

  • IdP (Okta): Authenticates users and sends assertions about their identity.
  • SP (Better Auth): Validates assertions and logs the user in.up.

Step 1: Create a SAML Application in Okta

  1. Log in to your Okta Admin Console

  2. Navigate to Applications > Applications

  3. Click "Create App Integration"

  4. Select "SAML 2.0" as the Sign-in method

  5. Configure the following settings:

    • Single Sign-on URL: Your Better Auth ACS endpoint (e.g., http://localhost:3000/api/auth/sso/saml2/sp/acs/sso). while sso being your providerId
    • Audience URI (SP Entity ID): Your Better Auth metadata URL (e.g., http://localhost:3000/api/auth/sso/saml2/sp/metadata)
    • Name ID format: Email Address or any of your choice.

  6. Download the IdP metadata XML file and certificate

Step 2: Configure Better Auth

Here’s an example configuration for Okta in a dev environment:

const ssoConfig = {
  defaultSSO: [{
    domain: "localhost:3000", // Your domain
    providerId: "sso",
    samlConfig: {
      // SP Configuration
      issuer: "http://localhost:3000/api/auth/sso/saml2/sp/metadata",
      entryPoint: "https://trial-1076874.okta.com/app/trial-1076874_samltest_1/exktofb0a62hqLAUL697/sso/saml",
      callbackUrl: "/dashboard", // Redirect after successful authentication
      
      // IdP Configuration
      idpMetadata: {
        entityID: "https://trial-1076874.okta.com/app/exktofb0a62hqLAUL697/sso/saml/metadata",
        singleSignOnService: [{
          Binding: "urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect",
          Location: "https://trial-1076874.okta.com/app/trial-1076874_samltest_1/exktofb0a62hqLAUL697/sso/saml"
        }],
        cert: `-----BEGIN CERTIFICATE-----
MIIDqjCCApKgAwIBAgIGAZhVGMeUMA0GCSqGSIb3DQEBCwUAMIGVMQswCQYDVQQGEwJVUzETMBEG
...
[Your Okta Certificate]
...
-----END CERTIFICATE-----`
      },
      
      // SP Metadata
      spMetadata: {
        metadata: `<md:EntityDescriptor xmlns:md="urn:oasis:names:tc:SAML:2.0:metadata" 
          entityID="http://localhost:3000/api/sso/saml2/sp/metadata">
          ...
          [Your SP Metadata XML]
          ...
        </md:EntityDescriptor>`
      }
    }
  }]
}

Step 3: Multiple Default Providers (Optional)

You can configure multiple SAML providers for different domains:

const ssoConfig = {
  defaultSSO: [
    {
      domain: "company.com",
      providerId: "company-okta",
      samlConfig: {
        // Okta SAML configuration for company.com
      }
    },
    {
      domain: "partner.com", 
      providerId: "partner-adfs",
      samlConfig: {
        // ADFS SAML configuration for partner.com
      }
    },
    {
      domain: "contractor.org",
      providerId: "contractor-azure",
      samlConfig: {
        // Azure AD SAML configuration for contractor.org
      }
    }
  ]
}

Explicit: Pass providerId directly when signing in. Domain fallback: Matches based on the user’s email domain. e.g. user@company.com → matches company-okta provider.

Step 4: Initiating Sign-In

You can start an SSO flow in three ways:

1. Explicitly by providerId (recommended):

// Explicitly specify which provider to use
await authClient.signIn.sso({
  providerId: "company-okta",
  callbackURL: "/dashboard"
});

2. By email domain matching:

// Automatically matches provider based on email domain
await authClient.signIn.sso({
  email: "user@company.com",
  callbackURL: "/dashboard"
});

3. By specifying domain:

// Explicitly specify domain for matching
await authClient.signIn.sso({
  domain: "partner.com",
  callbackURL: "/dashboard"
});

Important Notes:

  • DummyIDP should ONLY be used for development and testing
  • Never use these certificates in production
  • The example uses localhost:3000 - adjust URLs for your environment
  • For production, always use proper IdP providers like Okta, Azure AD, or OneLogin

Step 5: Dynamically Registering SAML Providers

For dynamic registration, you should register SAML providers using the API. See the SSO Plugin Documentation for detailed registration instructions.

Example registration:

await authClient.sso.register({
  providerId: "okta-prod",
  issuer: "https://your-domain.com",
  domain: "your-domain.com",
  samlConfig: {
    // Your production SAML configuration
  }
});

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