TypeScript 7.0 Is Rewriting the Compiler in Go
For most of its history, TypeScript has been written in TypeScript. The compiler, the language service, the checker — all JavaScript, all running on a single thread inside Node.js. That's changed now. TypeScript 7.0, shipped by Microsoft on July 8, 2026, replaces that entire implementation with a native compiler written in Go, developed under the internal codename Corsa . There's no new operator,…
TypeScript 7.0, released by Microsoft on July 8, 2026, marks a significant shift in the language's implementation. For the first time, the compiler, language service, and checker are all written in Go, a native compiler dubbed "Corsa." This move eliminates the previous reliance on JavaScript running on Node.js and introduces native code execution and multi-threaded parallelism.
The change is aimed at improving performance, particularly for large monorepos where the existing TypeScript compiler, tsc, would often grind to a halt. Microsoft evaluated several options before settling on Go, weighing its advantages as the lowest-level language that still supports native-code execution on all required platforms, with strong built-in support for concurrency.
The team chose to port the existing compiler faithfully to minimize the risk of introducing subtle type-checking differences. Performance improvements are substantial, with full builds for large projects showing an 8x to 12x speedup. Editor startup times have dropped dramatically, from around 9.6 seconds to about 1.2 seconds, and memory usage has reduced by 6% to 26% depending on project size.
The new binary, distributed as @typescript/native-preview, can be installed alongside the existing TypeScript package, allowing teams to switch incrementally and compare output before fully migrating.
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