CheckgateOpen-Source Feature Flags, Built for Speed.

Sub-microsecond local evaluation. Zero evaluation latency. Complete data privacy. The ultimate self-hosted alternative for feature toggles.

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Sub-Microsecond Evaluation

Flags are evaluated entirely in-process from an in-memory store. Zero network latency on every isEnabled() call — no HTTP round-trips, no polling.

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Fully Self-Hosted

Deploy on your own infrastructure with Docker. Your flag data never leaves your servers. Single binary, PostgreSQL, and Redis are all you need.

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Real-Time Updates via SSE

Flag changes propagate instantly to all connected SDK clients through Server-Sent Events. No polling interval — changes land in milliseconds.

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Advanced Targeting Rules

Target users by any attribute — email domain, plan, region, custom properties. Combine targeting rules with percentage rollouts for fine-grained control.

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Rust-Powered Core

The evaluation engine is written in Rust and compiled to native code (NAPI for Node.js, WASM for browsers, FFI for Flutter/React Native).

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Open Source & MIT Licensed

No black boxes, no usage limits, no surprise pricing. Fork it, extend it, and own your feature flag infrastructure completely.