MIT licensed
Free to use in any project, commercial or personal. No licensing fees, no restrictions.
v2.0
GoRules Version 2 is here - redesigned, now with managed cloud.GoRules Version 2 is here!
Watch the launch videoWatchThe open-source
rules engine.
The ZEN engine is fully open source and MIT licensed. Embed high-performance rule evaluation directly in your applications, with native bindings for every major language.
1.5k+ stars 100+ forks 8 languages
One core.
Native everywhere.
Every SDK is a thin native binding over the same Rust core - no HTTP overhead, no separate process, the same answers in every runtime.
In-process evaluation - no network hop, no per-evaluation fees.
Choose your
language.
Native SDK bindings for every major programming language. Same engine, same performance, familiar APIs.
Node.js
Node.js, Deno, and Bun with full async support.
Get startedPython
A Pythonic API with no GIL limits on evaluation.
Get startedGo
Thread-safe engine you can share across goroutines.
Get startedRust
The core itself - zero-cost abstractions, async-ready.
Get startedJava
JNI bindings for Spring Boot and the JVM.
Get startedKotlin
Coroutine support and an idiomatic Kotlin API.
Get startedC#
.NET 8+ via NuGet, async/await throughout.
Get startedSwift
On-device evaluation for iOS, offline-capable.
Get startedWhy
open source?
Transparency over trust-us. The open engine gives you full control of how your rules are evaluated - and where.
Rust core
Written in Rust for performance and memory safety. Zero garbage collection pauses.
Native bindings
Direct FFI bindings for each language. No HTTP overhead or separate processes.
Cross-platform
Runs on Linux, macOS, and Windows, on both ARM and x86.
Battle tested
Used by companies processing millions of decisions daily in production.
No vendor lock-in
Own your evaluation stack. Self-host anywhere, no external dependencies or API calls.
Own your
decision stack.
MIT licensed, self-hosted anywhere, no per-evaluation fees. Add the BRMS when you need governance.