SAML (Security Assertion Markup Language) is the long-established enterprise SSO standard. SAML 2.0 (the current version, published 2005) defines how an identity provider (Okta, Microsoft Entra ID, Ping, OneLogin) authenticates a user and passes a signed assertion to a service provider (your customer portal) without the service provider ever seeing the user’s password.
SAML is universally supported by enterprise identity providers. It’s older than OIDC and more verbose (XML-based), but for B2B customer portals it remains the most-requested SSO protocol because enterprise IT teams already configure SAML for hundreds of other applications.
In a portal implementation, the most important mapping is not the login button but the relationship between the SAML identity, the customer’s tenant, and the user’s role. Decide how email changes, duplicate accounts, certificate rotation, and just-in-time provisioning are handled before launch.
Use SAML when your enterprise customers require it. For a new consumer-facing or mobile application, OIDC is usually the more natural protocol.
See our portal authentication guide for SAML implementation patterns.