OpenFeature is a vendor-neutral specification and set of SDKs for feature flagging. It decouples the feature-flag API your application calls from the backend that actually evaluates the flags, so switching between LaunchDarkly, Flagsmith, Split, ConfigCat, Unleash, GO Feature Flag, or a self-hosted implementation becomes a provider swap rather than a code rewrite.
The spec defines a small, typed evaluation API — getBooleanValue, getStringValue, getObjectValue, etc. — along with an EvaluationContext for passing user and request attributes, and a hooks system for cross-cutting concerns like logging, telemetry, and validation. Providers implement a narrow interface; the SDK plugs them in at runtime. There are official SDKs for Java, .NET, Go, JavaScript/Node, Python, Ruby, PHP, and Rust, plus a daemon called flagd that speaks a gRPC evaluation protocol so languages without a native SDK can still participate. OpenFeature also publishes OpenTelemetry semantic conventions for feature-flag evaluation, so flag decisions can land on existing traces and metrics without custom instrumentation.
OpenFeature was accepted into the CNCF in 2022, reached incubating status in 2023, and is Apache-2.0. Its position in the ecosystem is similar to what OpenTelemetry is to observability or SQL to databases: a common surface over a competitive market of backends.