PyPy: Python in Python Implementation

Welcome to PyPy!

PyPy is both an implementation of the Python programming language, and an extensive compiler framework for dynamic language implementations. You can build self-contained Python implementations which execute independently from CPython.

The home page is:


If you want to help developing PyPy, this document might help you:


It will also point you to the rest of the documentation which is generated from files in the pypy/doc directory within the source repositories. Enjoy and send us feedback!

the pypy-dev team <pypy-dev@python.org>


First switch to or download the correct branch. The basic choices are default for Python 2.7 and, for Python 3.X, the corresponding py3.X branch (e.g. py3.5).

Build with:

$ rpython/bin/rpython -Ojit pypy/goal/targetpypystandalone.py

This ends up with a pypy-c or pypy3-c binary in the main pypy directory. We suggest to use virtualenv with the resulting pypy-c/pypy3-c as the interpreter; you can find more details about various installation schemes here: