Apply JSON-Patches (RFC 6902)

https://github.com/stefankoegl/python-json-patch

Identify specific nodes in a JSON document (RFC 6901)

https://pypi.org/project/jsonpointer/

Implementation of JSON Reference for Python

https://pypi.org/project/jsonref/

JSON Schema validation for Python

https://github.com/Julian/jsonschema

Serializer for JSON-like data in Python

https://github.com/RussellLuo/jsonsir

Creates JUnit XML documents used by tools such as Jenkins

https://github.com/kyrus/python-junit-xml

Store and access your passwords safely

https://github.com/jaraco/keyring

Alternate Python keyring implementations

https://pypi.org/project/keyrings.alt/

Kitchen contains a cornucopia of useful code

https://pypi.org/project/kitchen/

Fast implementation of the Cassowary constraint solver

https://github.com/nucleic/kiwi

Modern parsing library

https://github.com/lark-parser/lark

Lexer and codec to work with LaTeX code in Python

https://github.com/mcmtroffaes/latexcodec

Create configuration schemas, and process and validate configurations

https://launchpad.net/lazr.config

Easily write objects that delegate behavior

https://launchpad.net/lazr.delegates

Additional Launchpad web services using wadllib

https://launchpad.net/lazr.restfulclient

Library for parsing, manipulating, and generating URIs

https://launchpad.net/lazr.uri

Fast and thorough lazy object proxy

https://github.com/ionelmc/python-lazy-object-proxy

Library for programs conforming to DNS RFCs and drafts

https://www.nlnetlabs.nl/projects/ldns/

Python interface to libarchive

https://github.com/Changaco/python-libarchive-c

libpeas Python support

http://live.gnome.org/libpeas

Python bindings for Libvirt virtualization API

https://libvirt.org/python.html

Python interface for XML parser library for GNOME

http://xmlsoft.org/

Parses, normalizes and compares license expressions

https://github.com/nexB/license-expression

New features in linecache backported to Python 2

https://pypi.org/project/linecache2/

Small personal collection of python utility functions

https://github.com/alexmojaki/littleutils

Python bindings for low-level FUSE API

https://bitbucket.org/nikratio/python-llfuse

Platform-independent file locking module

https://github.com/smontanaro/pylockfile

Toolkit for logging of library method calls

https://github.com/ppolewicz/logfury

Handlers for the Python standard library logging package

https://bitbucket.org/vinay.sajip/logutils/

Pythonic binding for the libxml2 and libxslt libraries

https://lxml.de/

Python binding for the LZ4 compression library

https://github.com/python-lz4/python-lz4

Python binding for the LZMA compression library

http://www.joachim-bauch.de/projects/python/pylzma

Convert markdown formatted file with reST markup to reST format

https://github.com/miyakogi/m2r

Python module for determining file type

https://www.darwinsys.com/file/

Wrapper for email standard library

https://github.com/SpamScope/mail-parser

Super-fast templating language in Python

http://www.makotemplates.org/

Implements an RFC-5804 Manage Sieve client

https://bitbucket.org/ericvsmith/managesieve3

Python implementation of Markdown

https://pythonhosted.org/Markdown/

Python port of markdown-it

https://github.com/executablebooks/markdown-it-py

Fast and complete Python implementation of Markdown

http://code.google.com/p/python-markdown2/

Implements XML/HTML/XHTML Markup safe string for Python

https://github.com/pallets/markupsafe

Simplified object serialization for Python

https://marshmallow.readthedocs.io/en/stable/ https://github.com/marshmallow-code/marshmallow

Plotting library uses a syntax familiar to MATLAB users

https://matplotlib.org/

Build and publish crates with pyo3, rust-cpython and cffi bindings

https://github.com/PyO3/maturin

Ned's script to check McCabe complexity

https://pypi.org/project/mccabe/

Collection of plugins for markdown-it-py

https://github.com/executablebooks/mdit-py-plugins

Markdown URL utilities

https://github.com/executablebooks/mdurl

Python interface to Sendmail milter API

https://pythonhosted.org/milter/

Fastest markdown parser in pure Python

https://github.com/lepture/mistune

Fastest markdown parser in pure Python

https://github.com/lepture/mistune