Welcome to PyPy

PyPy is a fast, compliant alternative implementation of the Python language (2.7.13 and 3.5.3). It has several advantages and distinct features:

Speed: thanks to its Just-in-Time compiler, Python programs often run faster on PyPy. (What is a JIT compiler?)

“If you want your code to run faster, you should probably just use PyPy.” — Guido van Rossum (creator of Python)

Memory usage: memory-hungry Python programs (several hundreds of MBs or more) might end up taking less spacethan they do in CPython.

Compatibility: PyPy is highly compatible with existing python code. It supports cffi and can run popular python libraries like twisted and django.

Stackless: PyPy comes by default with support for stackless mode, providing micro-threads for massive concurrency.

As well as other features.