T3 Stack author @theo open-sourced "tsc-rs", a complete Rust port of the TypeScript compiler/type checker/LSP
It is not a compiler designed from scratch. It is a line-by-line port of Microsoft's official TypeScript 7 (typescript-go, the native Go version), which "preserves Go's algorithms and behavior." The pinned upstream commit is typescript-go@673a5f17. Licensed under MIT, retaining the upstream Apache-2.0 / BSD-3 notices.
Open-source repo: https://github.com/pingdotgg/ts-rust
Key numbers
Performance (Apple M4 Pro, hyperfine, median of 5 runs, 120 real open-source repos + a 60-project test set): compared to tsc 7 (Go), tsc-rs is about 1.61× faster, and bun check is about 2.95× faster.
Compatibility: all 181,711 tests ported from Go pass; across the 120 open-source repos, CLI output matches the Go version (except for a few known edge cases such as monorepo rootDir and tsc -b incremental output). The 10 errors reported by VS Code and the 2 errors reported by Sentry match TypeScript 7.1.0-dev exactly; bun check reports 3 extra in Sentry and 2 extra in tRPC.