# pypyjs/pypyjs

PyPy compiled to JavaScript

Repository: https://github.com/pypyjs/pypyjs
Canonical: https://ross.abutalabs.com/products/pypyjs
Language: Python
License: MIT
License Family: permissive
Last push: 2019-03-19T18:28:41+00:00

## Health v2 (maintenance only)
Score: 23/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 4651, "days_push": 2724, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1847, forks 115 (observed 2026-08-28T04:05:43.581631+00:00)

## What it is
PyPy.js is the PyPy Python interpreter compiled to JavaScript via an experimental emscripten/asm.js backend, allowing Python to run in the browser with JIT compilation to JavaScript at runtime. It is an experimental project whose development is currently sleeping, with Pyodide recommended as a maintained alternative.

## Use cases
- run python code in the browser
- execute python scripts client-side without a server
- embed a python interpreter in a web page
- try python live in a browser demo
- compile pypy to javascript

## When to choose
- you need a historical or experimental python-in-browser implementation
- you want to study emscripten/asm.js compilation of a large interpreter

## When to avoid
- you need a maintained python-in-browser solution (use Pyodide instead)
- you need production reliability or recent Python version support
- you need small bundle sizes or fast startup

## Facets
- artifact type: library
- maturity: abandoned
- function: interpreter, compiler
- domain: programming-languages, web-development, compilers
- platform: browser, wasm
- tags: python-in-browser, emscripten, asmjs, pypy, jit, javascript

## Member repositories
- pypyjs/pypyjs (main) score 23

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:43.581631+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 2026-08-30T03:17:51.039100+00:00, confidence not recorded.
  - readme: https://github.com/pypyjs/pypyjs (fetched 2026-08-28T04:05:43.581631+00:00, sha a1dad06ae8ff)
- Data as of 2026-08-30T08:39:29.467469+00:00.