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: [█████████████░░░░░░░] 62.7% (7,884/12,574 tests)

Conformance is measured by diagnostic fingerprint comparison: each diagnostic must match tsc in error code, file, line, column, and message.

Emitter

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

JavaScript:  [██████████████░░░░░░] 71.3% (9,710 / 13,623 tests)
Declaration: [████████░░░░░░░░░░░░] 39.0% (776 / 1,989 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: [████░░░░░░░░░░░░░░░░] 18.3% (1,204 / 6,564 tests)

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