ty

Judgement

What it is

Developer tool

What it does

A Python type checker and language server written in Rust, aiming to check code far faster than mypy or Pyright.

Adopt it when

Type checking a large Python codebase is too slow with mypy or Pyright and you can tolerate a beta tool.

Watch out

It is in beta at version 0.0.x and does not yet match the typing-spec coverage of mypy or Pyright.

Ready for

Experimental

Runs as

Command line

Built with

Rust and Python

How established

Young: started 18 months ago, latest release 0.0.98.

What the license allows

You can build it into a product you sell, as long as you keep its copyright notice.

Judged on 2026-11-06 from the project's README and GitHub data. The license and age lines are worked out directly.

Built from

Follow it down: ty → CPython → GCC → LLVM project → runs on a microchip

How compilers were built, back to punched paper tape

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