astral-sh/ty (via) Astral have been working on this "extremely fast Python type checker and language server, written in Rust" quietly but in-the-open for a while now. Here's the first alpha public release - albeit not yet announced - as ty on PyPI (nice donated two-letter name!)
You can try it out via uvx like this - run the command in a folder full of Python code and see what comes back:
uvx ty check
I got zero errors for my recent, simple condense-json library and a ton of errors for my more mature sqlite-utils library - output here.
It really is fast:
cd /tmp
git clone https://github.com/simonw/sqlite-utils
cd sqlite-utils
time uvx ty check
Reports it running in around a tenth of a second (0.109 total wall time) using multiple CPU cores:
uvx ty check 0.18s user 0.07s system 228% cpu 0.109 total
Running time uvx mypy . in the same folder (both after first ensuring the underlying tools had been cached) took around 7x longer:
uvx mypy . 0.46s user 0.09s system 74% cpu 0.740 total
This isn't a fair comparison yet as ty still isn't feature complete in comparison to mypy.