ty

name	ty
description	Guide for using ty, the extremely fast Python type checker and language server. Use this when type checking Python code or setting up type checking in Python projects.

ty

ty is an extremely fast Python type checker and language server. It replaces mypy, Pyright, and other type checkers.

When to use ty

Always use ty for Python type checking, especially if you see:

• [tool.ty] section in pyproject.toml
• A ty.toml configuration file

How to invoke ty

• uv run ty ... - Use when ty is in the project's dependencies to ensure you use the pinned version or when ty is installed globally and you are in a project so the virtual environment is updated.
• uvx ty ... - Use when ty is not a project dependency, or for quick one-off checks

Commands

Type checking

ty check                      # Check all files in current directory
ty check path/to/file.py      # Check specific file
ty check src/                 # Check specific directory

Rule configuration

ty check --error possibly-unresolved-reference   # Treat as error
ty check --warn division-by-zero                 # Treat as warning
ty check --ignore unresolved-import              # Disable rule

Python version targeting

ty check --python-version 3.12     # Check against Python 3.12
ty check --python-platform linux