Authentication is rebuilt in almost every project — login, roles, OAuth, sessions — costing weeks and often introducing subtle security flaws. AuthShield solves this by providing a single, production-grade authentication service that can be integrated into any application via APIs, eliminating the need to rebuild auth from scratch.
Built with FastAPI, PostgreSQL, and Redis, the system follows a clean layered architecture (API → Service → Repository → Infrastructure). It uses short-lived JWT access tokens and rotating refresh tokens with reuse detection, ensuring both stateless performance and strong security guarantees.
Redis powers token blacklisting, rate limiting, OAuth state validation, and temporary auth flows with sub-millisecond lookups. The system is fully containerized and ships with 48 integration tests running against real infrastructure, ensuring production reliability.
A key design highlight is the refresh token family model — any reuse of a compromised token instantly revokes the entire session chain, preventing silent account takeover and forcing re-authentication.