SAML vs OpenID Connect vs WS-Federation

SAML, OpenID Connect (OIDC), and WS-Federation are protocols used for Single Sign-On (SSO), allowing users to authenticate once and access multiple applications. While they serve a similar purpose, they differ in technology and modern usage. SAML (Security Assertion Markup Language) is an XML-based protocol widely used in enterprise environments for web-based SSO. It is mature, secure, and commonly used for corporate SaaS applications. OpenID Connect (OIDC) is built on OAuth 2.0 and uses JSON Web Tokens (JWT). It is lightweight and ideal for modern web, mobile, and cloud-native applications. Today, OIDC is the preferred choice for API-driven environments. WS-Federation is a SOAP/XML-based protocol mainly associated with older Microsoft environments, particularly legacy ADFS implementations. In simple terms, SAML is traditional enterprise SSO, OpenID Connect is modern cloud authentication, and WS-Federation is largely used in legacy Microsoft systems.