It's happening! A Python Type Checker from Astral

After months of speculation, Astral (creators of Ruff and uv) has officially announced their work on a new static type checker for Python. Built from the ground up in Rust, this tool aims to bring Astral’s signature focus on performance to Python’s static typing ecosystem.

Charlie Marsh, Astral founder, says that beyond performance, the project seeks to minimize “false positives, especially on untyped code, to make it easier for projects to adopt a type checker and expand coverage gradually over time, without being swamped in bogus type errors from the start.”

The prospect of a type checker integrating Ruff’s performance with native Python packaging addresses two key pain points of current type checkers — mypy’s slowness and Pyright’s JavaScript dependencies. No doubt Astral will bring us many more improvements beyond these.

Update: The tool has since been released as ty. See How to try the ty type checker to get started, or read How do mypy, Pyright, and ty compare? for a full comparison.