ts-migrate is a tool for helping migrate code to TypeScript. It takes a JavaScript, or a partial TypeScript, project in and gives a compiling TypeScript project out.

ts-migrate is intended to accelerate the TypeScript migration process. The resulting code will pass the build, but a followup is required to improve type safety. There will be lots of // @ts-expect-error, and any that will need to be fixed over time. In general, it is a lot nicer than starting from scratch.

ts-migrate is designed as a set of plugins so that it can be pretty customizable for different use-cases. Potentially, more plugins can be added for addressing things like improvements of type quality or libraries-related things (like prop-types in React).