SpiceDB is an open-source permissions database inspired by Google's Zanzibar, offering flexibility for building authorization schemes like RBAC, ABAC, or FGA. It uses a graph database to store relationships between objects according to a purpose-built schema, allowing developers to issue authorization queries to get answers to questions like "does user 123 have access to document 456?" A key challenge in FGA is determining the level of granularity needed for permissions data, with too much granularity leading to high maintenance costs and not enough granularity potentially limiting flexibility. SpiceDB's underlying guidance recommends modeling the smallest resource possible to achieve a balance between flexibility and maintainability, while also considering trade-offs when necessary. By doing so, developers can optimize their permission models to reduce unnecessary complexity and costs, ultimately leading to more efficient and scalable authorization systems.