Cerbos

The API accepts check requests with principal (user), resource, and action, and returns allow/deny decisions with the matched policy rule. Batch check requests enable efficient evaluation of multiple permissions in a single API call, which is important for agents that need to check a set of permissions before rendering an interface or executing a multi-step operation. The policy playground and audit logging provide inspection tools for debugging authorization decisions.

Reliability is excellent for the stateless deployment model. Each Cerbos instance evaluates policies independently without shared state — instances fail and recover independently without authorization system-wide impact. Policy updates are applied by reloading the PDP, which can be orchestrated with zero-downtime rolling restarts.

Cerbos is an open-source authorization policy decision point that evaluates fine-grained RBAC and ABAC policies against requests via REST or gRPC APIs. Policies are defined as YAML files and loaded by the stateless Cerbos PDP — the stateless design means Cerbos can be scaled horizontally for high-throughput authorization without shared state concerns. For agents requiring fast, reliable permission evaluation, Cerbos provides a self-hosted authorization service that can handle high request volumes without external latency.

Authentication to the Cerbos PDP is configured at the network level — Cerbos itself is typically deployed in a private network accessible only to application services. The self-hosted model means teams control the security perimeter for authorization infrastructure. Cerbos Hub (the managed service) adds centralized policy management with appropriate access controls.

Documentation is thorough and covers the policy schema, API, and deployment patterns clearly. The policy definition documentation is comprehensive — teams defining complex ABAC rules with conditions will find the expression language well-documented. Teams evaluating Cerbos versus Permit.io should weigh the open-source self-hosted model against Permit.io's managed service with UI-driven policy management.