mypy

Judgement

What it is

Developer tool

What it does

A static type checker for Python that reads type hints and reports type errors without running the code.

Adopt it when

A growing Python codebase uses type hints and you want the reference checker that most typing features land in first.

Watch out

It is slow on large projects compared with Pyright or newer Rust checkers, and untyped third-party libraries need stubs.

Ready for

Production-ready

Runs as

Command line

Built with

Python and mypyc

How established

Established: started 14 years ago, no tagged release yet.

What the license allows

GitHub could not read the license. Check it in the repository before reusing any code.

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: mypy → CPython → GCC → LLVM project → runs on a microchip

How compilers were built, back to punched paper tape

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