OpenFeature

OpenFeature standardizes the small piece of code every application has and nobody wants to own twice: the call that asks whether a flag is on. Each flag vendor ships its own SDK with its own idioms, so switching vendors means touching every evaluation site in the codebase. OpenFeature defines the evaluation API once and pushes the vendor behind a provider interface.

• Evaluation API - A common surface for boolean, string, number and object flags, with typed defaults.
• Providers - The vendor-specific adapter, swappable without touching application code.
• Evaluation context and hooks - A standard way to pass targeting attributes and to attach logging, telemetry or validation around every evaluation.
• OFREP - The OpenFeature Remote Evaluation Protocol, which does ship an OpenAPI definition — making it one of the few specifications in this catalog whose own wire surface is described the way it asks yours to be.

OpenFeature belongs in an API catalog because feature flags are how most API providers actually ship a breaking change — a new field, a new version, a changed default — to a subset of consumers before everyone. That makes flag state part of the effective contract, and an undocumented part of it. Read alongside OpenAPI and the versioning story: a contract that says one thing while a flag makes it behave another way is exactly the drift governance is supposed to catch.