GO Feature Flag

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.

Key Features

• Relay proxy (HTTP API) for multi-language support and central evaluation.
• Native Go module for in-process evaluation when using Go projects.
• Multiple retrievers: local file, HTTP, S3, Google Cloud Storage, Kubernetes ConfigMap, Git providers, Redis, MongoDB, PostgreSQL, and others.
• Advanced rollout strategies: targeted rules, canary releases, progressive (percentage) rollouts, scheduled changes, and A/B testing.
• Data exporters and notifiers to persist or forward evaluation events (file, S3/GCS, webhook, log) and notify via Slack/webhooks.
• Built to integrate with the OpenFeature standard to provide providers/SDKs across many languages.

Use Cases

• Add centralized feature flag evaluation for polyglot architectures using the relay proxy (HTTP API) and OpenFeature providers.
• Run progressive rollouts and A/B experiments with percentage-based and rule-based targeting while exporting evaluation events for analysis.
• Store flag configuration in existing infrastructure (S3, Git, Kubernetes, Redis, MongoDB, PostgreSQL) and deliver fast local or remote evaluations.

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.

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.