Auth0 implements proven, common and popular identity protocols used in consumer oriented web products (OAuth 2.0, OpenID Connect) and in enterprise deployments (SAML, WS-Federation, LDAP).
OAuth 2.0 is an authorization framework that enables a third-party application to obtain limited access to resources the end-user owns. It is about resource access and sharing.
OpenID Connect (OIDC) is an identity layer built on top of the OAuth 2.0 framework. It allows third-party applications to verify the identity of the end-user and to obtain basic user profile information. At the core, OIDC is about user authentication.
Security Assertion Markup Language (SAML) is an XML-based framework for authentication and authorization between two entities: a Service Provider and an Identity Provider. The Service Provider agrees to trust the Identity Provider to authenticate users. The Identity Provider authenticates users and provides to Service Providers an Authentication Assertion that indicates a user has been authenticated.
WS-Federation is part of the larger WS-Security framework and an extension to the functionality of WS-Trust. The features of WS-Federation can be used directly by SOAP clients and web services.
Lightweight Directory Access Protocol (LDAP) is an application protocol, used for accessing and maintaining distributed directory information services over an Internet Protocol (IP) network.