Permit.io supports both OPA and Cedar as policy engines, and the choice depends on your specific use case rather than one being universally "better." (1) (2) (3) *OPA (Open Policy Agent) * is a multipurpose policy engine that uses the Rego language. It's extremely flexible and can handle complex decisions across your entire stack. (2) (3) OPA excels at fine-grained permissions supporting RBAC, ABAC, and ReBAC (with certain adjustments) , and offers high performance with in-memory caching. (2) However, Rego has a significant learning curve as it's a logical programming language. ​*Cedar*​ is specifically tailored for application-level authorization and is designed to be highly readable. (2) (3) It emphasizes safety by default and provides structured, verification-guided development. (2) Cedar supports RBAC, ABAC, and ReBAC, and is particularly well-suited for fast ABAC-based decisions with built-in auditing and static analysis. (3) The trade-off is that Cedar currently has a smaller ecosystem and less established community compared to OPA. (2) Permit.io's platform works with both engines, abstracting their complexities through APIs, SDKs, and a no-code UI. (1) The platform also uses OPAL (Open Policy Administration Layer) to keep both OPA and Cedar updated in real-time with policy and data changes. (3) The decision comes down to your needs: if you want maximum flexibility across your stack and are willing to learn Rego, OPA is a strong choice. If you prioritize readability, determinism, and focus specifically on application-level authorization, Cedar may be more suitable. (1) (2)

To learn more, see the sources I considered: [[1] Policy Engine Showdown - OPA vs. OpenFGA vs. Cedar](https://www.permit.io/blog/policy-engine-showdown-opa-vs-openfga-vs-cedar) [[2] Policy Engines: Open Policy Agent vs AWS Cedar vs Google Zanzibar](https://www.permit.io/blog/policy-engines) [[3] OPA, Cedar, OpenFGA: Why are Policy Languages Trending Right Now?](https://www.permit.io/blog/opa-cedar-openfga-why-are-policy-languages-trending)