OAuth Authorization Server Built Without Storing User Profiles
The article details the evolution of an OAuth Authorization Server that deliberately avoids storing user profiles, relying instead on external identity providers for authentication. It addresses three core constraints: hundreds of dynamically created isolated APIs, a public SPA client without a BFF, and the inability of resources to query the AS on every request. The design separates concerns so the AS handles only clients, tenants, grants, audiences, scopes, keys, sessions, and token issuance while the Main API owns profiles and roles. Tokens are managed securely inside a Service Worker using a custom FedCM grant, eliminating races across tabs and reducing XSS exposure. The approach minimizes blast radius, simplifies compliance, and keeps the AS replaceable without affecting product domain logic.
Habr•Other
