# facebook/pyre-check

Performant type-checking for python.

Repository: https://github.com/facebook/pyre-check
Canonical: https://ross.abutalabs.com/products/pyre-check
Homepage: https://pyre-check.org/
Language: OCaml
License: MIT
License Family: permissive
Topics: python, typechecker, type-check, static-analysis, ocaml, code-quality, abstract-interpretation, security, program-analysis, taint-analysis, control-flow-analysis
Archived: true
Last push: 2026-06-26T16:04:19+00:00

## Health v2 (maintenance only)
Score: 10/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 89, release rhythm 8, longevity 100
- inputs: {"age_days": 3218, "days_push": 68, "days_rel": 673, "gap_med": null, "n_releases_24m": 1}
- flags: archived
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 7170, forks 452 (observed 2026-08-28T04:09:56.377922+00:00)

## What it is
Pyre is a performant, PEP 484-compliant static type checker for Python that provides incremental checking of large codebases, and it ships with Pysa, a taint-analysis tool for finding security vulnerabilities. The repository is now archived; type checking has moved to Pyrefly and Pysa to its own repository.

## Use cases
- type check a python codebase
- find type errors in python before runtime
- statically analyze python for security vulnerabilities
- detect taint flows from user input to dangerous sinks
- incremental type checking in the editor for large python projects

## When to choose
- you need fast, incremental PEP 484 type checking on very large Python codebases
- you want taint-analysis-based security scanning of Python code (via Pysa)
- you are maintaining a legacy setup already configured for Pyre

## When to avoid
- you are starting a new project - use Pyrefly (or mypy) for type checking and the standalone Pysa repo for security analysis
- you need actively maintained tooling with current Python version support
- you need cross-platform support beyond macOS and Linux

## Facets
- artifact type: cli-tool
- maturity: abandoned
- function: type-system, linter, security
- domain: developer-tools, programming-languages, security
- platform: python, cli
- tags: type-checker, pysa, taint-analysis, pep-484, archived, pyrefly-successor, python, macos, linux

## Member repositories
- facebook/pyre-check (main) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:09:56.377922+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T17:39:57.017868+00:00, confidence not recorded.
  - readme: https://github.com/facebook/pyre-check (fetched 2026-08-28T04:09:56.377922+00:00, sha d336a79acd67)
  - homepage: https://pyre-check.org/ (fetched 2026-08-29T08:35:14.191742+00:00, sha 6365ceed3cfe)
  - site_page: https://pyre-check.org/docs/getting-started (fetched 2026-08-29T08:35:14.200680+00:00, sha f1fa40fce50e)
  - site_page: https://pyre-check.org/docs/pysa-basics (fetched 2026-08-29T08:35:14.202636+00:00, sha 9ead37428c01)
- Data as of 2026-08-30T08:39:29.467469+00:00.