Resources
Pyrefly
Meta’s fast Rust-based Python type checker and language server, the default checker for Instagram’s Python codebase and now at a stable 1.x release
Pyright
Microsoft’s fast, standards-based static type checker for Python — a command-line tool and VS Code extension, and the engine behind Pylance
ty
Astral’s extremely fast Rust-based Python type checker and language server, from the makers of uv and Ruff — currently in beta
mypy
Optional static type checker for Python — catches type errors before runtime by analysing type annotations, with support for gradual typing