Sites like kiwitcms.org

Rescuezilla, an open-source disk imaging and cloning app with a graphical interface built on Clonezilla, distributed as a bootable live USB image

Appium documentation: an open-source software project for UI automation of mobile, browser and desktop apps

Dwi Siswanto's personal site with open-source security tools, bug bounty notes, songs and a sandboxing blog post by an Indonesian developer

Angelo Verlain's (vixalien) personal website: a blog of GJS, GNOME and open-source development posts, tutorials and yearly wrap-ups

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

WebdriverIO API reference documentation for the WebdriverIO browser and mobile test automation framework's commands and protocol bindings

A Java library documentation site for Instancio, a tool that generates random, fully populated test data objects

xUnit.net is an open source unit testing tool for C#, F# and Visual Basic, led by project lead Brad Wilson

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

Serenity/JS, a TypeScript-native framework and modular NPM packages for acceptance and end-to-end test automation with Playwright, WebdriverIO and Cucumber

Bugzilla project's website on the open-source bug-tracking software for planning and releasing software, with documentation, history and donation pages

Mocha, a JavaScript test framework for Node.js and browsers, with its project documentation and API reference

JUnit, a open-source testing framework for Java and the JVM, with documentation, release notes and project information

Reqnroll, an open-source Cucumber-style BDD test automation framework for .NET, with news and release announcements

Software Testing Weekly, a free weekly newsletter of curated software testing news, hand-picked by Dawid Dylowicz

A JavaScript testing framework named Jest, documented on its official site, with French and English pages and community help

A community hub for sustaining open source software, run by Richard Littauer, with a podcast, events and working groups

PHPUnit project website by Sebastian Bergmann covering the PHP testing framework, its releases, documentation, sponsors and community events

Matteo Collina's personal site on Node.js, with his open source projects, talks and the Adventures in Nodeland newsletter

A Go software co-op's collection of XMPP libraries and tools, including the mellium.im/cli and mellium.im/xml packages

A JavaScript library documentation site for Sinon.JS, offering stubs, spies, fakes and mocks for unit tests

A testing framework called Vitest, powered by Vite, with documentation for writing, mocking and configuring JavaScript tests

A catalog of open source JSON, YAML and TOML schemas used by editors and tools for validation and completion

fastlane is an open source tool for automating mobile app development, screenshots, beta distribution and store publishing

Vifm, an open-source terminal file manager with a Vim-like curses interface, documented and maintained by developer xaizek

SelectorsHub, a set of free browser tools and blog for software testers, led by founder Sanjay Kumar

Kislay Verma's blog "It Depends" on engineering at Shoffr, his MCP server and app launches, and side projects like Altmove chess

Waydroid, a free open-source project that runs a full Android system in a container on Wayland-based GNU/Linux desktops

GameCI is a open-source CI/CD tool and documentation site for automating game builds, tests and deployments

fast-check is a property-based testing library for JavaScript and TypeScript, with documentation and blog posts by maintainer Nicolas Dubien

Mockoon, a free open-source desktop app and CLI for designing and running mock APIs locally, plus the Mockoon Pro team service

Rhino Linux, an Ubuntu-based rolling-release Linux distribution with the Pacstall package manager and XFCE desktop, with downloads and documentation