Auth0 Single Sign-On

Single Sign-On (SSO) in the context of Auth0 refers to the ability for a user to log in once via Auth0 and gain access to multiple client applications without re-authentication, assuming those apps trust the same Auth0 Authorization Server.

Auth0 acts as the central authentication authority; when a user successfully logs in (or has an active SSO session), subsequent login attempts for other connected apps can bypass the login screen.

Key Capabilities

• Universal Login & shared session: Using Auth0’s Universal Login, an SSO cookie is set in the Auth0 domain after an initial authentication; subsequent app login flows check that cookie to decide whether to prompt login.

• Per-application SSO toggle / configuration: In Auth0, you can enable or disable SSO on a per-application basis (or tenant-wide for legacy tenants).

• Self-Service B2B SSO onboarding: For B2B use cases, Auth0 supports Self-Service SSO, where enterprise customers can configure their own SSO (SAML or OIDC) via a guided assistant; this creates an enterprise connection automatically.

Limitations

• Cookie / cross-domain constraints: The SSO cookie is bound to the Auth0 domain. Embedded login methods or cross-origin flows may fail under restrictive browser policies (e.g. third-party cookie blocking).

• Dependency on Auth0 availability: Because SSO centralizes authentication, any downtime of Auth0 impacts all connected applications.

• Per-application enablement nuance: Legacy tenants may have to manually enable SSO either tenant-wide or per application.

• Token / session lifetimes & refresh logic complexity: Managing token lifetimes, refresh tokens, expiration, and silent renewal (especially across multiple app sessions) requires careful design.

• Limitations in passwordless / connection types: Some flows (e.g. passwordless using email/sms) may not reuse existing SSO cookies and prompt login even if an SSO session exists.