Simple Feature Flagging for All | GO Feature Flag | WarmIndex

GO Feature Flag is a simple, complete, and lightweight self-hosted feature flag solution that is 100% open source.

🚀 Overview

GO Feature Flag provides developers with a straightforward way to implement feature flags without the complexity of SaaS platforms or heavy infrastructure. It uses a relay proxy to serve flags from various storage backends, enabling safe deployments, A/B testing, and progressive rollouts across multiple languages via the OpenFeature standard.

This project solves the problem of vendor lock-in and high costs associated with commercial feature flag services by offering a fully self-hosted, extensible alternative that integrates with your existing tools and workflows.

It is built for developers, engineering teams, and organizations—especially those working with Go or polyglot stacks—who want control, observability, and advanced targeting without sacrificing simplicity.

What problem does this project solve? Managing feature releases safely without code changes, reducing risks in deployments, and enabling experimentation.
Who is it built for? Developers and teams seeking open-source feature flagging for backend, frontend, and mobile apps.
Why did you build it? To create a lightweight, standards-compliant (OpenFeature) solution that's developer-friendly, avoiding complex setups and promoting community-driven innovation.

✨ Key Features

Advanced Rollouts: Progressive, scheduled, canary, and A/B testing strategies to release features gradually and monitor impact.
Complex Targeting: Rule-based targeting with a powerful query language (eq, in, AND/OR, etc.) for precise user segments.
Flexible Storage & Retrieval: Pull configs from file, GitHub/GitLab, S3, GCS, Kubernetes ConfigMaps, Redis, PostgreSQL, MongoDB, and more.
Usage Analytics & Notifications: Export flag evaluation data; get alerts via Slack, Discord, Teams, webhooks on config changes.
Multi-Language Support: OpenFeature providers for Go, JS/TS, Python, Java/Kotlin, .NET, Ruby, Swift, PHP, etc.
Optional: Flag linting CLI, WASM support (experimental in recent releases).

🛠 Tech Stack

Frontend: Web-based flag editor (https://editor.gofeatureflag.org), JavaScript/TypeScript SDKs.
Backend: Go (relay proxy and core library).
Database: PostgreSQL, Redis, MongoDB (as retrievers); flexible exporters to S3, Kinesis, PubSub, etc.
Auth: Custom (via config); OpenFeature standard.
Hosting: Docker, Kubernetes, self-hosted on Vercel/Cloudflare compatible infra.

👥 Who Is This For?

This project is useful for:

Developers who want to add feature flags to Go or multi-language apps without SaaS.
Teams looking for self-hosted solutions with A/B testing and analytics.
Indie makers building scalable apps needing safe, progressive releases.