A faster Python type checker written in Rust
$ pip install pyrefly && pyrefly init
Scale with Confidence
Type check over 1.85 million lines of code per second.ⓘTested using Meta infrastructure (166 cores, 228 GB RAM)
Developer Delight
Get lightning fast autocomplete, and catch errors with instant feedback in your favorite editor.
Easy Onboarding
Start type checking your code in minutes.
Performance Comparison
Type checking the PyTorch codebase from scratch.ⓘTested using Macbook
(10 cores: 8 performance + 2 efficiency cores, 32 GB RAM)
(10 cores: 8 performance + 2 efficiency cores, 32 GB RAM)
PyreflyⓘCommand: "pyrefly check"
Pyrefly uses as many threads as possible
Pyrefly uses as many threads as possible
PyrightⓘCommand: "pyright --threads=8"
8 threads yielded the best performance after testing multiple settings
8 threads yielded the best performance after testing multiple settings
MyPyⓘCommand: "dmypy run"