• JekyllinternetActiveMIT2026-07-05Jekyll core team — The static site generator that started the modern static web movement: plain text and templates become a complete site with no database or server-side code to break or be breached. It has powered GitHub Pages since 2008.
• JellyfinmultimediaActiveGPL-2.0-only2026-07-05Jellyfin team — Fully free media server for streaming your own films, shows, music and books to any device — a volunteer-run fork of Emby created when that project closed its source, with no accounts, tracking or paywalled features.
• Jitsi MeetcommunicationActiveApache-2.02026-07-05Jitsi community — Self-hostable video conferencing that runs entirely in the browser — no accounts, no apps, no data silo. During the 2020 shift to remote work it proved that critical communication infrastructure can be free software.
• KdenlivemultimediaActiveGPL-3.0-or-later2026-07-02KDE Community — KDE's non-linear video editor built on the MLT framework, with multi-track editing, proxy workflows and effects that have matured into genuine production capability. One of the longest-lived free video editors, in development since 2003.
• KeePassXCsecurityActiveGPL-2.0-only / GPL-3.0-only2026-07-02KeePassXC Team — Offline password manager keeping credentials in a strongly encrypted local database file, with browser integration, TOTP and hardware-key support. A community fork of KeePassX, it embodies the principle that secrets belong on your own disk, not in someone's cloud.
• KodimultimediaActiveGPL-2.0-or-later2026-07-05Kodi Foundation — Media center born as Xbox Media Center (XBMC) in 2002, turning any device into a home theatre with library management, add-ons and every codec imaginable. One of the longest-running community media projects.
• KritagraphicsActiveGPL-3.0-or-later2026-07-02Krita Foundation / KDE — Digital painting application from the KDE community, built by and for illustrators, comic artists and concept painters, with advanced brush engines and animation support. It grew from a KOffice component into one of the most respected free creative tools.
• LibreOfficeofficeActiveMPL-2.02026-07-02The Document Foundation — Full-featured free office suite — writer, spreadsheets, presentations, drawing, databases and math — and the home of the OpenDocument standard formats. Forked from OpenOffice.org in 2010 under The Document Foundation, it safeguards decades of documents from format lock-in.
• LibreWolfbrowsersActiveMPL-2.02026-07-05LibreWolf community — Community fork of Firefox stripped of telemetry and tuned for privacy out of the box, with uBlock Origin included and settings hardened by default. It shows how free licensing lets communities correct the course of even flagship software.
• libvirtsystemActiveLGPL-2.1-or-later2026-07-05libvirt.org community — Toolkit and daemon providing a stable, hypervisor-neutral API for managing virtual machines, storage and virtual networks — the management layer beneath most open source virtualisation stacks.
• Linux kernelsystemActiveGPL-2.0-only2026-07-02Linus Torvalds & contributors — The kernel started by Linus Torvalds in 1991 that, together with the GNU userland, powers most of the world's servers, all of the top-500 supercomputers, billions of Android devices and countless embedded systems. It is the largest collaborative software project in history.
• LLVMdevelopmentActiveApache-2.0 with LLVM exception2026-07-05LLVM Project — Compiler infrastructure whose reusable intermediate representation powers Clang, Rust, Swift, Julia and countless other languages and tools. Started as a university research project, now the shared foundation of modern compilation.
• LMMSmultimediaActiveGPL-2.0-or-later2026-07-05LMMS Developers — Digital audio workstation for pattern-based music production — synthesizers, samples, MIDI and automation in the tracker tradition, free since 2004. The first serious DAW many bedroom producers ever touched.
• LyXofficeActiveGPL-2.0-or-later2026-07-05LyX Team — Document processor built on the WYSIWYM principle — "what you see is what you mean" — combining a friendly editing interface with LaTeX's typesetting rigour underneath. Theses and books have been written in it for three decades.
• MariaDB ServerdatabasesActiveGPL-2.0-only2026-07-02MariaDB Foundation — Community-developed relational database created by MySQL's original authors on the day Oracle acquired Sun, precisely to keep the codebase free forever. Drop-in compatible with MySQL and the default database of most Linux distributions.
• MastodoncommunicationActiveAGPL-3.0-only2026-07-02Mastodon gGmbH — Decentralised social network server speaking the open ActivityPub protocol: thousands of independently run instances federate into one network no company can own or shut down. It became the flagship of the Fediverse and the practical alternative to centralised platforms.
• MinifluxinternetActiveApache-2.02026-07-05Frédéric Guillot — Minimalist self-hosted feed reader written in Go — a single binary that keeps RSS, the open protocol of the independent web, practical and alive after the death of centralised readers.
• Mozilla FirefoxbrowsersActiveMPL-2.02026-07-02Mozilla Foundation / Mozilla Corporation — Free and open source web browser developed by Mozilla, heir to the Netscape lineage and today the only major browser built on an engine (Gecko) that is not controlled by an advertising company. It popularised tabbed browsing and extensions, and it remains the reference point for an open, standards-driven and user-respecting web.
• Mozilla ThunderbirdcommunicationActiveMPL-2.02026-07-02MZLA Technologies / Mozilla Foundation — Free desktop email client from the Mozilla family with calendaring, contacts, chat and strong OpenPGP encryption built in. Revived by community donations after years of neglect, it is proof that users will directly fund software that respects them.
• mpvmultimediaActiveGPL-2.0-or-later2026-07-05mpv.io maintainers — Minimalist command-line media player descended from MPlayer/mplayer2, with a scriptable core, precise video output and no interface in the way. It is the playback engine inside dozens of other applications.