Pyrefly

Emerging

AI Coding

Visit

Heat Score

7-Day Change

+11

A.R.C. Grade

—

Pricing

free

Pyrefly is Meta's open-source Python type checker that analyzes large codebases using a Rust-powered inference engine, delivering faster performance than mypy or pyright.

Meta's open-source Python type checker built for speed. Analyzes large codebases faster than mypy or pyright with a Rust-powered inference engine.

What the signals say about Pyrefly

Pyrefly holds a HookFlow heat score of 33/100 in AI Coding, currently showing early-stage momentum building from a low base. Over the last 7 days its score moved +11 points (up). On the Lock-In Index it scores 100/100 (high lock-in, with significant switching cost).

Heat Score

0–100 viral momentum index combining social buzz, search trends & growth velocity

14-day trend

-2

24h

+11

30d

Computed from 1 live source in the latest pipeline run — more sources, higher confidence.

Heat Score Breakdown

Creator Buzz (30%)4

Search Interest (25%)11

Community Discussion (20%)4

Growth Momentum (25%)98

What is Pyrefly?

Pyrefly is an open-source Python type checker created by Meta. It uses a Rust-powered inference engine to analyze Python codebases faster than traditional type checkers like mypy and pyright.

How fast is Pyrefly compared to other type checkers?

Pyrefly is built for speed and analyzes large codebases faster than mypy or pyright, thanks to its Rust-powered inference engine.

Is Pyrefly free to use?

Yes, Pyrefly is free and open-source software.

What makes Pyrefly different from mypy and pyright?

Pyrefly uses a Rust-powered inference engine rather than a Python-based approach, enabling it to handle large codebases with faster analysis speeds than mypy or pyright.

A.R.C. Score

A.R.C. ratings are calculated for developer infrastructure and API-first tools. This tool hasn't been evaluated yet or falls outside the A.R.C. scope.

🔓Data Lock-In Index

100/ 100

Lower = more portable. 0 = fully open, 100 = maximum lock-in.

✗ Webhooks Out✗ Bulk Export✗ Open Formats

Pricing

free

Best For

Teams & Solo