
Hypertune
Type-safe feature flags platform with A/B testing, analytics, and app configuration optimized for TypeScript
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Lightweight, multi-language feature flag service with relay proxy
A simple, complete, self-hosted feature flag solution that supports Go, OpenFeature SDKs, and multiple storage backends, offering complex rollouts, notifications, and data export via a relay proxy.

GO Feature Flag is a lightweight, self‑hosted feature flag system designed for easy integration across polyglot environments. It can run as a Go module for in‑process evaluation or as a central relay proxy that exposes an API compatible with OpenFeature SDKs, enabling usage from languages such as Node.js, Java, and more.
Flags are defined in JSON, TOML, or YAML files and can be sourced from HTTP, S3, Kubernetes, or other supported locations. The platform supports complex rollout strategies—including percentage splits, A/B testing, scheduled activations, and progressive rollouts. Exporters send usage data to destinations like S3, Google Cloud Storage, or local files, while notifiers (webhook, Slack) alert teams to flag changes. Deployment is straightforward via Docker or binary execution, with the relay proxy listening on a configurable port.
Teams that need a flexible, code‑first flag management solution without a hosted SaaS UI will find GO Feature Flag ideal, especially when adopting the OpenFeature standard across multiple services.
When teams consider GO Feature Flag, these hosted platforms usually appear on the same shortlist.
Looking for a hosted option? These are the services engineering teams benchmark against before choosing open source.
Gradual rollout of a new API endpoint
20% of users receive the new endpoint, allowing safe validation before full release
A/B test UI redesign across web and mobile
Collect variation metrics via exporters to evaluate impact on user engagement
Feature gating for admin‑only functionality
Only users with the admin flag true can access the new admin panel
Scheduled feature activation for holiday promotion
Feature automatically enables on specified dates without code changes
Use the relay proxy for multi-language support and central flag management; Go-only projects can use the Go module directly.
Any language with an OpenFeature SDK, such as Go, Node.js, Java, .NET, and more.
Flags can be stored in JSON, TOML, or YAML files and retrieved from local files, HTTP endpoints, S3, Kubernetes ConfigMaps, etc.
Yes, GO Feature Flag can send change notifications via webhook or Slack integrations.
Flag definitions are managed through configuration files; there is no native UI, but you can build one or integrate external tools.
Project at a glance
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