Flipt — Git-Native Open-Source Feature Flag Management

Introduction

Flipt provides feature flag management without SaaS dependencies. It stores flag definitions in a local database or directly in Git repositories, enabling GitOps-driven feature rollouts where flag changes go through pull requests and code review.

What Flipt Does

• Manages boolean and multi-variate feature flags with a web UI and REST/gRPC API
• Supports percentage-based rollouts, segment targeting, and rule-based evaluation
• Stores flag configuration natively in Git for version control and audit trails
• Provides client SDKs and an OpenFeature provider for standardized evaluation
• Runs as a single binary with minimal resource requirements

Architecture Overview

Flipt is a single Go binary that serves a web UI, REST API, and gRPC API. Flag state can be stored in SQLite, PostgreSQL, MySQL, or CockroachDB. In Git mode, Flipt reads flag definitions from YAML files in a Git repository, polling for changes. The evaluation engine processes flag requests locally with sub-millisecond latency.

Self-Hosting & Configuration

• Single binary or Docker image with embedded SQLite for zero-dependency startup
• Supports PostgreSQL, MySQL, and CockroachDB for production database backends
• Git backend reads flag YAML from any Git repository with configurable poll intervals
• Authentication supports static tokens, OIDC, and Kubernetes service accounts
• Prometheus metrics endpoint and OpenTelemetry tracing for observability

Key Features

• Git-native flag storage enables GitOps workflows with PR-based flag changes
• Sub-millisecond local evaluation with no external network calls during flag checks
• OpenFeature provider for vendor-neutral integration across multiple feature flag tools
• Namespaces for organizing flags across teams and environments
• Audit log tracks every flag change with user, timestamp, and before/after state

Comparison with Similar Tools

• LaunchDarkly — Commercial SaaS with per-seat pricing; Flipt is free, self-hosted, and unlimited
• Unleash — Open-source but uses database-only storage; Flipt adds native Git backend for GitOps
• Flagsmith — Open-source with remote evaluation; Flipt evaluates locally for lower latency
• PostHog Feature Flags — Bundled with analytics; Flipt is a focused, lightweight flag service
• OpenFeature — A specification, not a product; Flipt implements OpenFeature as one of its SDKs

FAQ

Q: Does Flipt require a database? A: No. Flipt can run with an embedded SQLite database or read flag definitions directly from Git with no database at all.

Q: How does the Git backend work? A: Flipt polls a Git repository for YAML flag definition files. Changes pushed to the repo are picked up automatically without restarts.

Q: What is the evaluation latency? A: Evaluation happens locally within the Flipt server process, typically under 1ms for boolean and segment-based flags.

Q: Can Flipt handle percentage rollouts? A: Yes. Flipt supports percentage-based distribution rules that consistently assign entities to flag variants using hashing.

Sources

• https://github.com/flipt-io/flipt
• https://www.flipt.io/docs