APIs are crucial for modern applications, but managing their access and security policies can be challenging, especially when flexible, scalable, and fine-grained control is required. Open Policy Agent (OPA) offers a unified framework for defining and enforcing policies consistently across various platforms like microservices, APIs, and Kubernetes clusters. This consistent policy management is vital for security, compliance, consistency, and agility within enterprises. By utilizing an API gateway, such as Kong Gateway, as a central control point, organizations can enforce access control policies and other security measures uniformly, reducing the risk of misconfigurations and allowing developers to focus on business logic. For instance, instead of implementing access control logic in each microservice, policies can be centralized in the API gateway, which can integrate with identity management solutions like Keycloak to ensure only authenticated users have access, thus illustrating how centralized policy management streamlines API security and scalability.