Google replaces pytype with Pyrefly as its Python type checker

Google announced on 6 October 2026 that it is adopting Pyrefly, Meta's Rust-based Python type checker, across the company and dropping its own pytype. Google's internal benchmarks show Pyrefly an order of magnitude faster than pytype, with roughly 97% on the official typing conformance suite. The pytype repository was archived on 3 September 2026, with Python 3.12 as the last supported version.

• Pyrefly is written in Rust and is an order of magnitude faster than pytype, per Google
• Incremental rebuilds with a warm daemon are up to 98% faster
• Pyrefly scores roughly 97% on the official typing conformance suite
• The pytype repo was archived on 3 September 2026, with Python 3.12 the last supported version