Sites like matplotlib.org

NumPy project website: the official home of the open source Python library for numerical computing and N-dimensional arrays

SciPy, an open source Python library of algorithms for scientific computing, covering optimization, integration, interpolation, statistics and differential equations

Scikit-learn, an open-source Python library of machine learning tools for predictive data analysis, with documentation, FAQ and installation guides

A collection of free image processing algorithms and documentation for the scikit-image toolbox in Python

A documentation site for pytest, the Python testing framework, with a list of talks, books and tutorials about it

conda-forge: a community-run GitHub organization of conda recipes, packages and the Miniforge installer for software distribution

The HDF Group, a non-profit company maintaining the HDF5 data format and library for scientific and engineering data management

NumFOCUS, a nonprofit charity supporting open source scientific software projects such as SciPy, pandas and Jupyter

The pages came through as binary garbage with no readable titles or headings, so the site's subject can't be determined from them. Going only by the domain, python.org is the official home of the Python programming language

A documentation site for pre-commit, a framework for managing and running git pre-commit hook scripts before code review

Gensim, an open-source Python library for topic modelling and semantic vector representation of text, by Radim Řehůřek

Pocoo, a former team of open source developers behind Python projects Flask, Sphinx, Jinja, Werkzeug and Pygments

Kivy, an open-source Python framework for building cross-platform GUI apps, with a project blog, about page and documentation

MNE-Python, an open-source Python package for analyzing human neurophysiological data such as MEG and EEG

A project website for PyPy, an alternative implementation of the Python programming language with a just-in-time compiler

OpenCV, the open-source computer vision library, with its services, training, partner program and blog, run by the OpenCV organisation

The LaTeX Project's website on LaTeX, the document preparation and typesetting system for technical and scientific publishing, with downloads, bug reporting, help and licence text

A book by Serena Bonaretti teaching computational thinking through Python programming, with downloadable Jupyter notebooks for each chapter

Chiamaka Ikeanyi's personal blog and portfolio on accessibility, JavaScript and frontend engineering, plus her work history

The aiohttp.org site is the documentation and project page for aiohttp, an asynchronous Python HTTP client and server library built on asyncio

Personal academic website of Fredrik Johansson, researcher in computer algebra, covering his Arb arbitrary-precision library, publications and thesis

Selenium, an open-source browser automation tool for web application testing, documented on its official project website

Personal blog by Mike Driscoll sharing Python tutorials, code samples and files from his Python Extension Building Network projects

Stan, an open-source software project and documentation site for Bayesian statistical modeling and inference across several programming languages

Personal website of Sebastián Ramírez, a Colombian software developer, sharing ideas, guides and his open source projects like FastAPI

Green Tea Press, publisher of free programming, data science and modeling textbooks by Allen B. Downey

Homebrew, a package manager for installing software on macOS, Linux and WSL from the command line

DB Browser for SQLite, an open source visual tool for creating, searching and editing SQLite and SQLCipher database files

The MacPorts Project's official site offering a package manager for installing open-source software on macOS and other Unix-like systems

PsychoPy: open-source Python software and documentation for building and running psychology and neuroscience experiments, with a graphical Builder and scripting

Gephi, an open-source software project for visualizing and analysing network data through graph layouts, metrics and community detection

PyDev, an open source Eclipse plugin adding Python development support, created by Aleks Totic and maintained by Fabio Zadrozny

Bernát Gábor's blog and project pages on Python packaging, tox, virtualenv and other open-source tools, plus talks

A documentation site for APIFlask, a lightweight Python web API framework built on Flask, covering usage, tips and OpenAPI support

CourtBouillon, a French cooperative's catalogue of open source document tools such as the pydyf PDF creator and CSS parser

The Open Source Geospatial Foundation website, a nonprofit hub supporting geospatial open source software projects, their community, events and governance

SciML is an open source software organization building Julia tools for scientific machine learning, physics-informed AI and differentiable programming

Django Girls is a non-profit organization running free Python and Django programming workshops for women, with open online tutorials