ty

An extremely fast Python type checker and language server, written in Rust.

Type checking the <a href="https://github.com/home-assistant/core">home-assistant</a> project without caching.

ty is backed by Astral, the creators of uv and Ruff.

Highlights

10x - 100x faster than mypy and Pyright
Comprehensive diagnostics with rich contextual information
Configurable rule levels, per-file overrides, suppression comments, and first-class project support
Designed for adoption, with support for redeclarations and partially typed code
Language server with code navigation, completions, code actions, auto-import, inlay hints, on-hover help, etc.
Fine-grained incremental analysis designed for fast updates when editing files in an IDE
Editor integrations for VS Code, PyCharm, Neovim and more
Advanced typing features like first-class intersection types, advanced type narrowing, and sophisticated reachability analysis

Run ty with uvx to get started quickly:

shell

uvx ty check

ty will check all Python files in the working directory or project by default.

See the type checking documentation for more details.

To install ty, see the installation documentation.

To add the ty language server to your editor, see the editor integration guide.

ty has an online playground you can use to try it out on snippets or small projects.

!!! tip

The playground is a great way to share snippets with other people, e.g., when sharing a bug
report.