# ty

> ty is an extremely fast Python type checker.

ty is an extremely fast Python type checker written in Rust. It can type check
large Python codebases in seconds, providing fast feedback during development.

ty includes both a CLI (`ty check`) and a language server for editor integration.

When fetching documentation, use explicit `index.md` paths for directories, e.g.,
`https://docs.astral.sh/ty/features/index.md`. This returns clean markdown instead
of rendered HTML with JS/CSS.


## Guides

- [Editor integration](http://127.0.0.1:8000/ty/editors/index.md)
- [Installation](http://127.0.0.1:8000/ty/installation/index.md)
- [Type checking](http://127.0.0.1:8000/ty/type-checking/index.md)

## Concepts

- [Configuration](http://127.0.0.1:8000/ty/configuration/index.md)
- [File exclusions](http://127.0.0.1:8000/ty/exclusions/index.md)
- [Module discovery](http://127.0.0.1:8000/ty/modules/index.md)
- [Python version](http://127.0.0.1:8000/ty/python-version/index.md)
- [Rules](http://127.0.0.1:8000/ty/rules/index.md)
- [Suppression](http://127.0.0.1:8000/ty/suppression/index.md)

## Features

- [Diagnostics](http://127.0.0.1:8000/ty/features/diagnostics/index.md)
- [Language server](http://127.0.0.1:8000/ty/features/language-server/index.md)
- [Type system](http://127.0.0.1:8000/ty/features/type-system/index.md)

## Reference

- [CLI](http://127.0.0.1:8000/ty/reference/cli/index.md)
- [Configuration](http://127.0.0.1:8000/ty/reference/configuration/index.md)
- [Editor settings](http://127.0.0.1:8000/ty/reference/editor-settings/index.md)
- [Environment variables](http://127.0.0.1:8000/ty/reference/environment/index.md)
- [Exit codes](http://127.0.0.1:8000/ty/reference/exit-codes/index.md)
- [Rules](http://127.0.0.1:8000/ty/reference/rules/index.md)
- [Typing FAQ](http://127.0.0.1:8000/ty/reference/typing-faq/index.md)