Google Zanzibar: A Scalable Global Authorization System

Google's 2019 Zanzibar paper details a flexible and scalable global authorization system designed to handle Google's massive scale. It's inspired numerous similar products. Zanzibar's core lies in its flexible access control model and strong distributed consistency guarantees. Leveraging Google Spanner and TrueTime for consistency, and clever architectural designs (like zookies and the Leopard indexing system) for scalability, it tackles complex challenges. While its distributed nature and high consistency requirements might be overkill for most applications, its API design is influential, with many companies striving to create simpler, more accessible alternatives.