Wednesday, 29 July 2026 @ 16:01 UTC~1013,752154,727

Pyrefly

Meta·facebook.pyrefly

A fast type checker and language server for Python

Pyrefly is a type checker and language server for Python, which provides lightning-fast type checking along with IDE features such as code navigation, semantic highlighting, and code completion. It is available as a command-line tool and an extension for popular IDEs and editors such as VSCode, Neovim, Zed, and more.

winget install --id facebook.pyrefly --exact --source winget

Latest 1.1.1·June 19, 2026

Release Notes

Release date: June 18, 2026

Pyrefly v1.1.1 is a patch release with a single bug fix.

🐛 Bug fixes

  • #3867: Fixed a regression introduced in 1.1.0 where isinstance() narrowing of a union variable

silently stopped working when an earlier sibling branch in the same if/elif/else chain narrowed a different variable with isinstance() and returned. The later narrowing left the union untouched, producing false missing-attribute errors on code that checked correctly in 1.0.0.

Thank-you to all our contributors who found these bugs and reported them! Did you know this is one of the most helpful contributions you can make to an open-source project? If you find any bugs in Pyrefly we want to know about them! Please open a bug report issue here.

Installer type: zip

x64—D54E29B9F49877D2937710C975996CF00E6576F0A10EC4C84C9F6C370CA396A8
arm64—F75EB69610C76DF17C4A2279961003D896ECD4F880CA02F211F4ADE39F451FEC

Details

Homepage
https://github.com/facebook/pyrefly
License
MIT
Publisher
Meta
Support
https://github.com/facebook/pyrefly/issues
Copyright
Copyright (c) Meta Platforms, Inc. and affiliates.

Tags

code-qualitycontributions-welcomegood-first-issuehacktoberfestidelanguage-serverlsppythonrusttype-checktype-checkertypechecktypecheckertypestyping