ts-r
Fast TypeScript tooling, written from scratch in Rust. ts-r type-checks, lints, bundles,
runs and serves TypeScript, aiming for the same results as the tools you use today, and faster:
ts-r-check type-checks tRPC, date-fns and RxJS 2.0–5.4× faster than tsc 7 (benchmarks).
Each tool is its own small binary and works on its own next to tsc, ESLint and Vite, so
you can adopt one without the rest.
npm install --save-dev @ts-r.dev/cli@next # the ts-r launcher and every tool
npx ts-r check # type check, with tsc 7's diagnostics
npx ts-r lint # lint, with ESLint and typescript-eslint rules
npx ts-r build # bundle, with esbuild's CLI
npx ts-r run server.ts # run TypeScript (replaces tsx / ts-node)
npx ts-r dev # dev server with HMR and Vite's import.meta.hot
Status: preview. The type checker is the most mature tool. It gives tsc 7's exact output on
97.7% of TypeScript's own conformance tests. It also matches tsc 7 exactly on tRPC, date-fns,
TypeORM and Playwright, and is within a few diagnostics on RxJS (none extra, 5 missing, of
about 21,900). Every other tool works on real projects
but has known gaps (below). Version numbers stay below 1.0 until that changes.
Contents
The tools
| Tool | Replaces | Works today | Known gaps |
|---|
ts-r-check | tsc (type checking, emit, --build, --watch) | tsc 7's codes, messages and chains; JavaScript, declaration and source-map emit; project references | Some inference and narrowing; 3.0% of conformance tests still differ |
ts-r-lint | ESLint, oxlint | 814 rules, 61 of them type-aware on ts-r's own checker; 90,430 of 90,461 cases of ESLint's, typescript-eslint's, eslint-plugin-jsdoc's, eslint-plugin-unicorn's and eslint-plugin-import's own tests pass; flat config, oxlint and Biome configs | Type-aware rules only where ts-r-check matches your tsc; plugins other than typescript-eslint (and 74 eslint-plugin-jsdoc, 369 eslint-plugin-unicorn and 46 eslint-plugin-import rules) |
ts-r-build | esbuild, vite build | esbuild's CLI flags; ESM, CJS and IIFE output; code splitting; minification; source maps; --watch | No plugins, no CSS bundling, lowering down to ES2015 (not ES5) |
ts-r-run | tsx, ts-node | Runs TypeScript on Node 22.15+ with tsc 7's JavaScript output | Only the entry's tsconfig is used |
ts-r-dev | vite dev | Hot reload, Vite's import.meta.hot API, React Fast Refresh, dependency pre-bundling, vite.config and Vite plugins | No CSS preprocessors; some vite.config options and plugin APIs; HTTP/1.1 only |
ts-r-lsp | tsserver, the ESLint server | One server per workspace for lint and types; our checker or your own TypeScript as the type backend | Most projects still fall back to tsserver for diagnostics |
ts-r | | Launcher for all of the above, plus ts-r ci (check, lint and build in parallel) and ts-r doctor | |
What each tool matches, and how it is measured: each crate's AGENTS.md and the design records
in docs/design/.
Install
Every tool is an npm package with a native binary for macOS (arm64, x64), Linux (arm64, x64;
glibc and musl) and Windows (arm64, x64). Install one, or the ts-r launcher (@ts-r.dev/cli) with all of them:
npm install --save-dev @ts-r.dev/cli@next # every tool and the ts-r launcher
npm install --save-dev @ts-r.dev/check@next # just ts-r-check (or run, dev, build, lint, lsp)
To type-check with ts-r wherever your scripts and tools already run tsc, use the drop-in
typescript package. It runs ts-r-check where ts-r-check gives the same result as your own
TypeScript on that project, and hands everything else to your TypeScript:
// package.json
"devDependencies": {
"typescript": "npm:@ts-r.dev/typescript@next",
"typescript-real": "npm:typescript@^7.0.0"
}
During the alpha, use @next or an exact version (@7.0.1000-alpha.3): a range like ^7
doesn't match prerelease versions.
The details are in npm/typescript/README.md. Packages and platforms
are in npm/ts-r/README.md.
Benchmarks
Each table shows ts-r's median time per scenario next to the fastest other tool on the same
workload. Workloads include type-checking pinned open-source repos (tRPC, date-fns, rxjs) and
bundling three.js ten times over, among others. Pull requests that change the crates or the
benchmarks are benchmarked against their base on GitHub's runners: Linux x64 is the gate, and
Linux arm64, Windows x64 and arm64 and macOS on Apple silicon and Intel report alongside it. A
slowdown beyond the gate fails the bench check, which reviewers read before merging. Method
and scenarios: bench/README.md.
Unreleased (main)
| Benchmark | ts-r | Fastest other tool | ts-r is |
|---|
version-startup | ts-r 2.03 ms | esbuild 3.93 ms | 1.9× faster |
check-trpc | ts-r-check 474 ms | tsc-7 979 ms | 2.1× faster |
check-date-fns | ts-r-check 998 ms | tsc-repo 1.97 s | 2.0× faster |
check-rxjs | ts-r-check 1.20 s | tsc-7 6.51 s | 5.4× faster |
build-three-x10 | ts-r-build 963 ms | esbuild 1.41 s | 1.5× faster |
Medians on linux-x86_64 (four dedicated cores), measured 2026-10-24. Scenarios: bench/scenarios.toml and bench/repos.toml.
The table above is written from one review-box bench of a pull request
(node scripts/readme-bench.mjs main): this one is #42's, at d8a6a97 (merged as 8b6c630),
whose code differs from main's only in ts_r_run, which none of these scenarios runs. The one
below is the same table at the time of the latest release, and is updated by each release pull
request.
Latest release
Release v0.1.0-alpha.5:
| Benchmark | ts-r | Fastest other tool | ts-r is |
|---|
version-startup | ts-r 2.03 ms | esbuild 3.93 ms | 1.9× faster |
check-trpc | ts-r-check 474 ms | tsc-7 979 ms | 2.1× faster |
check-date-fns | ts-r-check 998 ms | tsc-repo 1.97 s | 2.0× faster |
check-rxjs | ts-r-check 1.20 s | tsc-7 6.51 s | 5.4× faster |
build-three-x10 | ts-r-build 963 ms | esbuild 1.41 s | 1.5× faster |
Medians on linux-x86_64 (four dedicated cores), measured 2026-10-24. Scenarios: bench/scenarios.toml and bench/repos.toml.
How it works
Every layer is written in this repo, with no other compiler, bundler or linter underneath:
lexer, parser, binder, type checker, transformer, code generator, minifier, module resolver,
bundler, linter, dev server and language server. TypeScript's, esbuild's and ESLint's test suites
and outputs are the oracles: ts-r runs them and compares, and does not copy their code.
| Path | What it is |
|---|
crates/ts_r_lexer, ts_r_parser, ts_r_ast | Error-recovering parser for TS, TSX and JS into a compact, index-based AST |
crates/ts_r_binder, ts_r_checker | Scopes and symbols; the type checker |
crates/ts_r_transform, ts_r_codegen, ts_r_emit | TypeScript to JavaScript, printing, source maps and declaration files |
crates/ts_r_resolver, ts_r_config | Node and TypeScript module resolution; tsconfig.json |
crates/ts_r_bundler, ts_r_minify | The bundler and minifier behind ts-r-build and ts-r-dev |
crates/ts_r_lint | Lint rules and config loading |
crates/ts_r_lsp, editors/vscode | Language server and the VS Code extension |
docs/design/ | Design records: why each piece works the way it does |
AGENTS.md has the full crate map and the rules every change follows.
Build from source
You need the Rust toolchain pinned in rust-toolchain.toml (rustup installs it) and Node 22 or
newer for the tests that compare against tsc and esbuild.
git clone https://github.com/Webb-Ventures/typescript-rust
cd typescript-rust
cargo xtask upstream sync --minimal # TypeScript's lib files, which the checker tests need
cargo build --release # binaries in target/release
cargo test --workspace
cargo xtask also runs the oracles (cargo xtask oracle), the benchmarks (cargo xtask bench)
and the top-npm-packages harness (cargo xtask ecosystem). See xtask/AGENTS.md.
Contributing
Contributions are welcome: bug reports, mismatches with tsc or ESLint, and pull requests.
- CONTRIBUTING.md: how to set up, the checks a change must pass, and how
pull requests are reviewed and merged.
- AI_POLICY.md: AI-assisted work is welcome from Anthropic's, OpenAI's and Meta's
Muse models only. Pull requests that credit any other model are closed automatically.
- CODE_OF_CONDUCT.md and SECURITY.md (report vulnerabilities
privately).
- CHANGELOG.md: what changed in each release.
Sponsors
ts-r is free and open source, and its development is funded by sponsors.
Sponsor ts-r: if ts-r saves your team time, support its development.
Sponsors are listed here.
License
ts-r is MIT licensed (LICENSE). Unless you say otherwise, any contribution you submit
for inclusion in ts-r is licensed under MIT, with no additional terms or conditions.
TypeScript's lib files shipped with ts-r-check and ts-r-lsp are under TypeScript's own
Apache-2.0 license, included next to them. Upstream test data fetched by
cargo xtask upstream sync stays in the gitignored target/ directory under its own license.
