Flipt is a self-hosted, open-source feature flag service written in Go. Unlike LaunchDarkly or Statsig, it’s a single binary you run yourself, with no SaaS dependency, which makes it popular with teams that don’t want customer or evaluation data leaving their infrastructure.
The server exposes REST and gRPC APIs for flag evaluation and management, backed by SQLite, Postgres, MySQL, or CockroachDB. Flags can be boolean or multivariate, and rule-based targeting is driven by arbitrary context attributes that the client passes on every evaluation. Flipt v2 introduced a “declarative / GitOps” mode where flag state lives in a Git repo as YAML and the server watches it, so flag changes go through pull requests and audit comes for free. There are also native client SDKs that pull flag state and evaluate fully client-side for low-latency use.
Flipt is OpenFeature-compatible and ships an OpenFeature provider, so you can swap it behind standard SDKs without rewriting application code. Its natural competitors are Unleash (also self-hosted, Node.js), OpenFeature’s own reference providers, and the hosted SaaS flag vendors. If you want “feature flags without a vendor” and are comfortable running a Go binary and a database, Flipt is the straightforward pick.