Private API

A private API is an API used only within an organization - between internal services, teams, or applications. It is not published to external developers and does not require the same level of documentation, backward compatibility, or security hardening as a public API.

Private APIs are the backbone of microservices architectures - each service exposes a private API consumed only by other services in the same platform. They enable teams to build independently while still integrating through well-defined interfaces.

The distinction between private and public APIs has significant implications for design and maintenance. Private APIs can be changed more freely since all consumers are known and internal. Public APIs must treat breaking changes as a major versioning event requiring advance notice.