Zanzibar: How One Simple Data Model Handles Two Trillion ACLs in Milliseconds

Zanzibar reveals how Google's unified authorization system handles 2 trillion ACLs with sub-10ms latency—essential knowledge for architects designing permission systems at scale. By consolidating fragmented service-level access controls into a single tuple-based engine, Google solved the consistency and correctness challenges that plague distributed systems. The system's influence is evident in SpiceDB and OpenFGA's adoption, underscoring its practical significance for modern infrastructure.