# facebookincubator/MetaPython

This is Meta's fork of the CPython runtime.  The name "cinder" here is historical, see https://github.com/facebookincubator/cinderx for the Python extension / JIT compiler.

Repository: https://github.com/facebookincubator/MetaPython
Canonical: https://ross.abutalabs.com/products/metapython
Language: Python
License: NOASSERTION
License Family: other
Topics: interpreter, jit, python, compiler, runtime
Last push: 2026-08-26T18:07:44+00:00

## Health v2 (maintenance only)
Score: 77/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 35, longevity 100
- inputs: {"age_days": 1996, "days_push": 7, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases, no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 3789, forks 137 (observed 2026-08-28T04:08:18.696354+00:00)

## What it is
Meta's fork of the CPython runtime (historically named Cinder), maintained by Facebook Incubator. It tracks upstream Python 3.14+ and pairs with the separate cinderx project for the Python extension and JIT compiler.

## Use cases
- run python with a jit compiler for faster execution
- use meta's optimized cpython fork in production
- try cinder python runtime performance improvements
- build a custom python interpreter from source
- experiment with python runtime modifications

## When to choose
- you need faster python execution via jit and want a drop-in cpython-compatible runtime
- you want to experiment with or contribute to python runtime-level optimizations
- your infrastructure already uses Meta's python tooling

## When to avoid
- you just need a standard python interpreter - use upstream CPython
- you depend on strict upstream CPython compatibility and third-party wheels
- you want a stable, officially supported python distribution

## Facets
- artifact type: cli-tool
- maturity: active
- function: interpreter, compiler
- domain: programming-languages, compilers, performance, developer-tools
- platform: windows, cpp, python, cross-platform
- tags: cpython-fork, jit, python-runtime, meta, cinder, interpreter, linux, macos

## Member repositories
- facebookincubator/MetaPython (main) score 77

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:08:18.696354+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 2026-08-30T08:31:28.705364+00:00, confidence not recorded.
  - readme: https://github.com/facebookincubator/MetaPython (fetched 2026-08-28T04:08:18.696354+00:00, sha e486f7006ae6)
- Data as of 2026-08-30T08:39:29.467469+00:00.