Project Zang

Project Zang is a performance-first TypeScript compiler in Rust.1 The goal is a correct, fast, drop-in replacement for tsc, with both native and WASM targets.

TypeScript is intentionally unsound. Zang keeps a sound core solver and layers a compatibility engine on top to match TypeScript behavior while preserving correctness where possible.

Progress

[!WARNING] This project is not ready for general use yet.

Currently targeting TypeScript@6.0.0-dev.20260215

Type Checker

To ensure tsz is a drop-in replacement for tsc, we run the official TypeScript conformance test suite against it.

Progress: [███████████████░░░░░] 73.2% (9,210/12,574 tests)

Emitter

We compare tsz JavaScript/declaration emit output against TypeScript's baseline files to ensure correct code generation.

JavaScript:  [█████████████░░░░░░░] 66.5% (8,848 / 13,315 tests)
Declaration: [███████░░░░░░░░░░░░░] 34.5% (663 / 1,923 tests)

Language Service

We run TypeScript's fourslash language service tests against tsz-server to measure language service feature coverage (completions, quickinfo, go-to-definition, etc.).

Progress: [███░░░░░░░░░░░░░░░░░] 14.6% (957 / 6,564 tests)

1: "Zang" is the Persian word for "rust".