# ty

> ty is an extremely fast Python type checker.

ty is an extremely fast Python type checker and a language server 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 (`ty 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

- [Coming from mypy, pyright](https://docs.astral.sh/ty/coming-from-mypy-or-pyright/index.md)
- [Editor integration](https://docs.astral.sh/ty/editors/index.md)
- [Installation](https://docs.astral.sh/ty/installation/index.md)
- [Type checking](https://docs.astral.sh/ty/type-checking/index.md)

## Concepts

- [Configuration](https://docs.astral.sh/ty/configuration/index.md)
- [File exclusions](https://docs.astral.sh/ty/exclusions/index.md)
- [Module discovery](https://docs.astral.sh/ty/modules/index.md)
- [Python version](https://docs.astral.sh/ty/python-version/index.md)
- [Rules](https://docs.astral.sh/ty/rules/index.md)
- [Suppression](https://docs.astral.sh/ty/suppression/index.md)

## Features

- [Diagnostics](https://docs.astral.sh/ty/features/diagnostics/index.md)
- [Language server](https://docs.astral.sh/ty/features/language-server/index.md)
- [Type system](https://docs.astral.sh/ty/features/type-system/index.md)

## Reference

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