pyre-check vs mypy
Python type checkers, with different project status and scope
pyre-check and mypy both check Python code against type information and report potential type errors without requiring the code to run. The key difference is that pyre-check is archived and its type-checking role has moved to Pyrefly, while mypy remains an active project and focuses on static type checking with gradual typing.
pyre-check: Check Python Types and Find Data Flows
Pyre is an incremental, performant type checker for Python, with Pysa for security-focused data-flow analysis. The repository is archived: type checking has moved to Pyrefly, and Pysa is maintained in a separate repository.
mypy: Check Python Types Without Running Your Code
mypy is a static type checker that finds type-related issues in Python code before it runs. Add type hints incrementally, then use mypy locally or in a development workflow to catch mistakes and make code easier to maintain.
| pyre-check | mypy | |
|---|---|---|
| Language | OCaml | Python |
| License | MIT | NOASSERTION |
| Stars | 7.2k | 20.7k |
| Forks | 450 | 3.3k |
| Last analyzed | Oct 3, 2026 | Oct 3, 2026 |
Key differences
- pyre-check is archived; mypy is not archived.
- pyre-check documents Pysa for security-focused data-flow analysis, now maintained separately; mypy focuses on type checking.
- pyre-check is implemented in OCaml, while mypy is implemented in Python.
- pyre-check uses annotations in line with PEP 484; mypy supports gradual adoption of type hints and lists features including type inference, generics, and structural subtyping.
- pyre-check requires Python 3.9 or later and Watchman according to its documented setup; mypy offers command-line checks, daemon mode, editor integrations, and an online playground.
- The metadata lists pyre-check under the MIT license and mypy as NOASSERTION; mypy also has more reported stars and forks.
Choose pyre-check if you…
- maintain an existing Pyre setup or need a reference for a legacy configuration.
- need to understand Pyre's incremental checking or its documented Pysa data-flow analysis.
- plan to evaluate Pyrefly for type checking or the separate Pysa repository for current data-flow analysis.
Choose mypy if you…
- want an unarchived project for Python static type checking.
- prefer to introduce type hints gradually and check annotated code during development.
- want command-line checks, daemon mode, or integrations with editors and development tools.
Compare the numbers side by side, or add more projects
This comparison is generated with AI from the OSRepos analyses of both projects. Always check each project's repository and documentation before choosing.