GO Feature Flag

GO Feature Flag is a 100% open-source, self-hosted feature-flagging solution created by French engineer Thomas Poignant. It evaluates Bool, String, Int, Double and JSON flags from configuration files stored on local disk, HTTP, S3 or Kubernetes in JSON, TOML or YAML format, with no requirement to run a separate management backend. Built-in features include scheduled flag changes, A/B testing with audience splitting, percentage rollouts and metrics export. Originally a Go library, it now exposes 15+ language SDKs and integrates fully with the OpenFeature standard. There is no paid tier; the project is MIT-licensed.