ty — Python Type Checker and Language Server

Overview

ty is an extremely fast Python type checker and language server written in Rust, developed by Astral (the creators of uv and Ruff). It provides 10x–100x faster type checking than mypy and Pyright, with comprehensive diagnostics, configurable rule levels, per-file overrides, suppression comments, and first-class project support.

Key Features

• Speed: 10x–100x faster than mypy and Pyright
• Comprehensive diagnostics with rich contextual information
• Configurable rule levels (error, warn, ignore) with per-file overrides
• Suppression comments: # ty: ignore[rule], # type: ignore, # type: ignore[ty:rule]
• Designed for adoption: supports redeclarations and partially typed code
• Language server with code navigation, completions, code actions, auto-import, inlay hints, hover, signature help, semantic highlighting, code folding, notebook support
• Fine-grained incremental analysis for fast IDE updates (milliseconds, even on large projects)
• Editor integrations: VS Code, Neovim, Zed, PyCharm, Emacs, and any LSP-compatible editor
• Advanced typing features: first-class intersection types, advanced type narrowing, sophisticated reachability analysis
• Jupyter Notebook support (.ipynb files)
• Online playground at play.ty.dev