Cloudflare and VoidZero Introduce tsrs: An AI-Generated Rust Port

Cloudflare has announced tsrs, a Rust port of the TypeScript compiler it is developing with VoidZero and Max Schwenk of Owner.com. The work sits inside the Oxc toolchain, in close collaboration with the TypeScript team, and Cloudflare is emphatic it is not a fork: that team retains full control over the language's design. InfoQ's report by Daniel Curtis, published on 27 October 2026, cites up to 8x faster type checking and around 70% less memory than TypeScript 7.0.

Developers who type-check an existing repo, including people who own the CI check, are the readers for what follows. The piece gives Owner.com's monolith numbers, an independent npm comparison, ImportStatic's TypeScript 7.1 beta result, the npm and npx commands, and the experimental limits: no watch mode, no language server, no --init or --showConfig, and an exit code unlike tsc. It also places tsrs next to Microsoft's tsgo and Theo Browne's tsc-rs.

What Cloudflare and VoidZero shipped

@tsrs/wasm is the WebAssembly build, so checks can run in a browser or on Workers without dragging a garbage collector into the bundle the way a Go binary does. The port ships beside Microsoft's Go-based compiler, tsgo, and Theo Browne's tsc-rs. Cloudflare is merging tsc-rs and tsrs into a single package and adding language server and content mapper support. Daniel Rosenwasser said much of the speed "does not just come down to language choice," and that some optimisations discovered in tsrs are feeding a leaner TypeScript 7.1.

What changed for builders in Cloudflare and VoidZero

Owner's 37,000-file monolith needed 19 GiB and 80 seconds on TypeScript 7.0 and dropped to 7 seconds on tsrs. A separate npm-package benchmark measured 5.3x faster checking and 72% less memory, with identical diagnostics and byte-identical emit. Peter Steinberger moved to tsrs over the weekend, called it a drop-in replacement, and reported around 5x faster checks for OC. He wrote that Microsoft took a team and two years to rewrite the TypeScript compiler in Go, while an agent produced something significantly better within weeks.

Against the TypeScript 7.1 beta, ImportStatic measured 2.7x, a smaller gain than the 8x figure taken against TypeScript 7.0 at the same number of checker workers. The npm test that matched diagnostics and emit also showed tsrs exiting with code 2 on type errors where tsc exits 1, enough to quietly break a CI script that expects 1. Others questioned whether the arena-based, never-freed memory model is sound. Daniel Rosenwasser said some optimisations discovered in tsrs are feeding a leaner TypeScript 7.1.

How to install or upgrade Cloudflare and VoidZero

Install tsrs as a dev dependency and aim it at the tsconfig already in the tree. The announcement's two commands are a local install and a no-emit check of the current directory. The -p . flag selects that project. The --noEmit flag skips writing output. The two commands below are the whole published try-out. Teams still on TypeScript 5 or TypeScript 6 should adopt Microsoft's native Go port first, because tsrs tracks TypeScript 7, and only then swap this package in.

npm install -D tsrs

npx tsrs -p . --noEmit

After the Go port is in place, migration reuses the existing tsconfig. --init and --showConfig are both unsupported, and diagnostic order can differ from tsc. With watch mode absent, the npx line is one check and then an exit. The language server is not in this build, so editor features that need one stay on the TypeScript tools already in the repo. Language server and content mapper support are what Cloudflare is adding by merging tsc-rs and tsrs into one package.

Gotchas and compatibility in Cloudflare and VoidZero

Watch mode is missing, and so is a language server. --init and --showConfig are unsupported, and diagnostic order can differ from tsc. The status code is the sharper mismatch. The benchmark that found 5.3x faster checking, 72% less memory, identical diagnostics, and byte-identical emit also found tsrs exiting 2 on type errors while tsc exited 1. A CI script that expects exit code 1 can break once the binary changes. The release is experimental, so these differences are in the package a developer installs now.

What to watch after Cloudflare and VoidZero

Cloudflare is combining Theo Browne's tsc-rs and tsrs into one package and adding language server and content mapper support there. Watch mode, --init, and --showConfig remain unavailable in the experimental release. Peter Steinberger wrote: "Moved to tsrs over the weekend. Drop-in replacement. Around 5x faster for OC." He also wrote that it took Microsoft a team and two years to rewrite the TS compiler in Go, and that you can "let an agent rip and get sth significantly better within weeks." TypeScript 7.1 is already taking optimisations discovered in tsrs.

Schwenk's account names the method with counts attached. He wrote "zero" code, directed agents led by Claude Opus 5.5, and used 15,197 TypeScript conformance cases as the spec. On Owner's 37,000-file monolith, TypeScript 7.0 took 19 GiB and 80 seconds, and tsrs took 7 seconds. The code is Apache-2.0 on GitHub. A pipeline has to treat exit code 2 as the type-error status, because tsc uses 1. Browser and Workers runs use @tsrs/wasm so the bundle does not pick up a garbage collector the way a Go binary does.