GO Feature Flag
Lightweight open-source feature flag system with a relay proxy, OpenFeature support, file/cloud retrievers, and exporters for usage data.

GO Feature Flag is an open-source feature flag solution that provides a Go module and a relay-proxy API server to evaluate and manage flags across languages. It supports file and cloud retrievers, progressive rollouts, A/B testing and event export for flag usage tracking. (gofeatureflag.org)
Key Features
- Relay proxy (HTTP API) for multi-language support and central evaluation. (github.com)
- Native Go module for in-process evaluation when using Go projects. (github.com)
- Multiple retrievers: local file, HTTP, S3, Google Cloud Storage, Kubernetes ConfigMap, Git providers, Redis, MongoDB, PostgreSQL, and others. (gofeatureflag.org)
- Advanced rollout strategies: targeted rules, canary releases, progressive (percentage) rollouts, scheduled changes, and A/B testing. (gofeatureflag.org)
- Data exporters and notifiers to persist or forward evaluation events (file, S3/GCS, webhook, log) and notify via Slack/webhooks. (github.com)
- Built to integrate with the OpenFeature standard to provide providers/SDKs across many languages. (gofeatureflag.org)
Use Cases
- Add centralized feature flag evaluation for polyglot architectures using the relay proxy (HTTP API) and OpenFeature providers. (github.com)
- Run progressive rollouts and A/B experiments with percentage-based and rule-based targeting while exporting evaluation events for analysis. (gofeatureflag.org)
- Store flag configuration in existing infrastructure (S3, Git, Kubernetes, Redis, MongoDB, PostgreSQL) and deliver fast local or remote evaluations. (gofeatureflag.org)
Limitations and Considerations
- OpenFeature integration is a cornerstone of multi-language support; users should validate current provider coverage and compatibility for their target language since OpenFeature is evolving. (github.com)
GO Feature Flag is geared toward teams that want a lightweight, auditable, and extensible self-hosted feature flag system with first-class Go support and a language-agnostic HTTP relay. The project provides editor tooling for composing and testing flags and is maintained as an open-source project with community contributions. (editor.gofeatureflag.org)
