PyPy is a fast, compliant alternative implementation of the Python language (2.7.1). It has several advantages and distinct features:

• Speed: thanks to its Just-in-Time compiler, Python programs often run faster on PyPy.
• Memory usage: large, memory-hungry Python programs might end up taking less space than they do in CPython.
• Compatibility: PyPy is highly compatible with existing python code. It supports ctypes and can run popular python libraries like twisted and django.
• Sandboxing: PyPy provides the ability to run untrusted code in a fully secure way.
• Stackless: PyPy can be configured to run in stackless mode, providing micro-threads for massive concurrency.
• As well as other features.