version 7.3.7 is compatible with three CPython versions: 2.7, 3.7 and 3.8. The first PyPy version compatible with CPython v3 is PyPy v2.3.1 (2014). The PyPy interpreter compatible with CPython v3 is also known as PyPy3. PyPy has JIT compilation support on 32-bit/64-bit x86 and 32-bit/64-bit ARM processors. It is tested nightly on Windows, Linux, OpenBSD and Mac OS X. PyPy is able to run pure Python software that does not rely on implementation-specific features. There is a compatibility layer for CPython C API extensions called CPyExt, but it is incomplete and experimental. The preferred way of interfacing with C shared libraries is through the built-in C foreign function interface (CFFI) or ctypes libraries. History PyPy is a followup to the Psyco project, a just-in-time specializing compiler for Python, developed by Armin Rigo between 2002 and 2010. PyPy's aim is to have a just-in-time specializing compiler with scope, which was not available for Psyco. Initially, the RPython could also be compiled into Java bytecode, CIL and JavaScript, but these backends were removed due to lack of interest. PyPy was initially a research and development-oriented project. Reaching a mature state of development and an official 1.0 release in mid-2007, its next focus was on releasing a production-ready version with more CPython compatibility. Many of PyPy's changes have been made during coding sprints. In August 2008, PyPy was able to run some popular Python libraries like Pylons, Pyglet, Nevow and Django. On 12 March 2010, PyPy 1.2 was released, focusing on speed. It included a working, though not yet stable, just-in-time compiler. On 30 April 2011, PyPy version 1.5 was released, which reached compatibility with CPython 2.7. On 9 May 2013, PyPy 2.0 was released, which introduced alpha-quality support for JIT compilation on ARMv6 and ARMv7 JIT, and included CFFI in the standard library. On 20 June 2014, PyPy3 was declared stable and introduced compatibility with the more modern Python 3. It was released alongside PyPy 2.3.1 and bears the same version number. On 21 March 2017, the PyPy project released version 5.7 of both PyPy and PyPy3, with the latter introducing beta-quality support for Python 3.5. On 26 April 2018, version 6.0 was released, with support for Python 2.7 and 3.5 (still beta-quality on Windows). On 11 February 2019, version 7.0 was released, with support for Python 2.7 and 3.5. On 14 October 2019, version 7.2 was released, with support for