Pyrefly
github.com/facebook/pyrefly- Category
- Developer Tools
- Type
- APP
- Builder
- GitHub
- 6.8k stars
- Added
- Jun 16, 2026
About
A fast type checker and language server for Python, from Meta.
Why it made the leaderboard
Pyrefly is a genuinely differentiated Python type checker that delivers 15x performance improvements over existing tools like Mypy and Pyright, with production validation at Meta/Instagram scale. It's built from scratch in Rust with comprehensive IDE integration and framework-specific support, representing a meaningful technical advancement rather than just another wrapper tool.
Tech Stack
Rust
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