Federated Identity: SAML, OAuth, and OpenID Connect

In modern enterprises, employees need to access dozens of applications — cloud apps, SaaS tools, partner portals, and internal systems — each potentially maintained by different organizations. Creating and managing separate accounts for each is insecure (credential proliferation) and inefficient. Federated identity solves this by allowing an Identity Provider (IdP) — a trusted, authoritative source of identity — to authenticate users and share that authenticated identity with Service Providers (SPs) across organizational boundaries. Users authenticate once and gain access to multiple systems without re-entering credentials.

Single Sign-On (SSO) allows users to authenticate once and access multiple applications within a session without re-authenticating. The user logs in to the Identity Provider (corporate Active Directory, Okta, Azure AD), receives a session token or assertion, and presents this token to each Service Provider they visit. SSO improves security by reducing the number of passwords users must manage (reducing reuse), enabling centralized authentication policy enforcement, and allowing immediate access revocation across all integrated applications when an account is disabled at the IdP level.