Waitress is a production-quality pure-Python WSGI server with very acceptable performance. It has no dependencies except ones which live in the Python standard library. It runs on CPython on Unix and Windows under Python 3.5+. It is also known to run on PyPy (version 3.5 compatible) on UNIX. It supports HTTP/1.0 and HTTP/1.1.
For more information, see the "docs" directory of the Waitress package or visit https://docs.pylonsproject.org/projects/waitress/en/latest/