How does Rails support high-scale identity and access management (IAM) systems?

Rails integrates IAM via OAuth2, JWT, SSO providers, and centralized policy engines.

At scale, authentication is decoupled into identity providers like Auth0, Keycloak, or Cognito. Rails acts as a relying party validating JWT tokens or session assertions. Authorization is often handled using policy engines like Pundit or external systems (OPA). IAM systems enforce role-based and attribute-based access control across microservices.