Checkgate is an open-source feature flag engine that evaluates flags locally — no network call, no latency, no SaaS vendor. Every flag decision happens inside your process in sub-microseconds, while a persistent SSE stream keeps every SDK instance in sync within 50 ms of a change.
It is proudly built in Rust and ships with native SDKs for Node.js (NAPI), browsers (WebAssembly), React Native (JSI), and Flutter (FFI). A persistent SSE stream propagates flag changes to every connected SDK instance in under 50 ms.
A flag change is written once, then pushed to every connected SDK in milliseconds — after which each isEnabled() is a local, in-process lookup.
- Sub-microsecond evaluation — flags are evaluated entirely in local memory
- Real-time updates — SSE push, not polling; changes land in < 50 ms
- Targeting rules — match by any user attribute (
email,plan,region, …) - Percentage rollouts — deterministic MurmurHash3 bucketing; sticky and independent per flag
- Rust evaluation core — compiled to NAPI, WASM, JSI, or FFI depending on platform
- Self-hosted — single binary + PostgreSQL + Redis; your data never leaves your infra
Indigo dashboard with the Checkgate gate logo, shown with example data for Vantage Robotics and administrator Juan Dela Cruz. Explore the dashboard guide.
Dashboard overview — flag counts, rollout status, and recent activity at a glance.
Feature flags — tags, types, rollout percentage, and one-click enable/disable per environment.
Flag editor — targeting rules, tags, ownership, and prerequisite (dependent) flags.
Change requests — require a second reviewer before a flag change takes effect in sensitive environments; self-approval is blocked.
Cross-environment diff — see what's different between environments before promoting, with a one-click sync.
Personal access tokens — scoped, revocable API credentials for CI/CD and Terraform, as an alternative to admin-equivalent SDK keys.
Environments — isolate configuration across Production, Staging, UAT, and Development, with per-environment approval gates.
Collapsible sidebar — reclaim screen space on data-dense pages; the whole dashboard is full-width by default.
| Topic | Link |
|---|---|
| Why Checkgate / comparisons | What is Checkgate? |
| System architecture | Architecture |
| Flags, rules, rollout concepts | Core Concepts |
| Dashboard tour | Dashboard |
| Step-by-step setup | Getting Started |
| REST API + SSE stream reference | API Reference |
| Node.js SDK | SDK: Node.js |
| Web (WASM) SDK | SDK: Web |
| React Native (JSI) SDK | SDK: React Native |
| Flutter (FFI) SDK | SDK: Flutter |
| Type-safe codegen CLI | @checkgate/cli |
| Edge evaluation (Workers, Fly.io) | @checkgate/edge |
| SSR / bootstrap (Next.js, Remix, …) | @checkgate/ssr |
| Terraform / OpenTofu provider | terraform-provider-checkgate |
| Kubernetes operator | checkgate-operator |
| Docker, AWS, env vars | Self-Hosting |
| Enterprise Setup & Migration | Enterprise Setup & Migration |
See CONTRIBUTING.md.
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