_See also: [Comparison of CalDAV and CardDAV implementations - Wikipedia](https://en.wikipedia.org/wiki/Comparison_of_CalDAV_and_CardDAV_implementations)_
- [Baïkal](https://sabre.io/baikal/) - Lightweight CalDAV and CardDAV server based on sabre/dav. ([Source Code](https://github.com/sabre-io/Baikal)) `GPL-3.0``PHP`
- [calypso](https://keithp.com/calypso/) - Python-based CalDAV and CardDAV server (fork of Radicale). ([Source Code](https://keithp.com/cgit/)) `GPL-3.0``Python`
- [DAViCal](https://www.davical.org/) - Server for calendar sharing (CalDAV) that uses a PostgreSQL database as a data store. ([Source Code](https://gitlab.com/davical-project/davical)) `GPL-2.0``PHP`
- [calypso](https://keithp.com/calypso/) - Python-based CalDAV and CardDAV server (fork of Radicale). ([Source Code](https://keithp.com/cgit/)) `GPL-3.0``Python/deb`
- [DAViCal](https://www.davical.org/) - Server for calendar sharing (CalDAV) that uses a PostgreSQL database as a data store. ([Source Code](https://gitlab.com/davical-project/davical)) `GPL-2.0``PHP/deb`
- [Davis](https://github.com/tchapi/davis) - A simple, dockerizable and fully translatable admin interface for sabre/dav based on Symfony 5 and Bootstrap 4, largely inspired by Baïkal. `MIT``PHP`
- [Etebase (EteSync)](https://www.etebase.com/) - End-to-end encrypted and journaled personal information server supporting calendar and contact data, offering its own clients. ([Source Code](https://github.com/etesync/server)) `AGPL-3.0``Python/Django`
- [EteSync Web](https://www.etesync.com/faq/#web-client) - EteSync's official Web-based client (i.e., their Web app). ([Demo](https://client.etesync.com/), [Source Code](https://github.com/etesync/etesync-web)) `AGPL-3.0``Javascript`
- [Manage My Damn Life](https://intri.in/manage-my-damn-life/) - Manage my Damn Life (MMDL) is a self-hosted front end for managing your CalDAV tasks and calendars. ([Source Code](https://github.com/intri-in/manage-my-damn-life-nextjs)) `GPL-3.0``Nodejs/Docker`
- [Radicale](https://radicale.org/) - Simple calendar and contact server with extremely low administrative overhead. ([Source Code](https://github.com/Kozea/Radicale)) `GPL-3.0``Python`
- [Radicale](https://radicale.org/) - Simple calendar and contact server with extremely low administrative overhead. ([Source Code](https://github.com/Kozea/Radicale)) `GPL-3.0``Python/deb`
- [SabreDAV](https://sabre.io/) - Open source CardDAV, CalDAV, and WebDAV framework and server. ([Source Code](https://github.com/sabre-io/dav)) `MIT``PHP`
- [Xandikos](https://github.com/jelmer/xandikos) - Open source CardDAV and CalDAV server with minimal administrative overhead, backed by a Git repository. `GPL-3.0``Python`
- [Xandikos](https://github.com/jelmer/xandikos) - Open source CardDAV and CalDAV server with minimal administrative overhead, backed by a Git repository. `GPL-3.0``Python/deb`
Multiplayer game servers and [browser games](https://en.wikipedia.org/wiki/Browser_game).
- [0 A.D.](https://play0ad.com/) - A free, open-source game of ancient warfare. ([Source Code](https://github.com/0ad/0ad)) `MIT/GPL-2.0/Zlib``C++/C`
- [0 A.D.](https://play0ad.com/) - A free, open-source game of ancient warfare. ([Source Code](https://github.com/0ad/0ad)) `MIT/GPL-2.0/Zlib``C++/C/deb`
- [A Dark Room](https://github.com/doublespeakgames/adarkroom) - Minimalist text adventure game for your browser. ([Demo](https://adarkroom.doublespeakgames.com/)) `MPL-2.0``HTML5`
- [EmuLinkerSF](https://emulinker.org) - EmuLinkerSF is an open source Kaillera server. Kaillera is a client/server system that any emulator can implement to enable netplay over the Internet. ([Source Code](https://github.com/God-Weapon/EmuLinkerSF)) `GPL-2.0``Java`
- [Lila](https://lichess.org/) - The forever free, adless and open source chess server powering lichess.org, with official iOS and Android client apps. ([Source Code](https://github.com/lichess-org/lila)) `AGPL-3.0``Scala`
- [Mindustry](https://mindustrygame.github.io/) - Factorio-like tower defense game. Build production chains to gather more resources, and build complex facilities. ([Source Code](https://github.com/Anuken/Mindustry)) `GPL-3.0``Java`
- [Minetest](https://www.minetest.net/) - An open source voxel game engine. Play one of our many games, mod a game to your liking, make your own game, or play on a multiplayer server. ([Source Code](https://github.com/minetest/minetest)) `LGPL-2.1/MIT/Zlib``C++`
- [Minetest](https://www.minetest.net/) - An open source voxel game engine. Play one of our many games, mod a game to your liking, make your own game, or play on a multiplayer server. ([Source Code](https://github.com/minetest/minetest)) `LGPL-2.1/MIT/Zlib``C++/deb`
- [MTA:SA](https://multitheftauto.com/) `⚠` - Multi Theft Auto (MTA) is a software project that adds network play functionality to Rockstar North's Grand Theft Auto game series, in which this functionality is not originally found. ([Source Code](https://github.com/multitheftauto/mtasa-blue)) `GPL-3.0``C++`
- [piqueserver](https://github.com/piqueserver/piqueserver) - Server for openspades, the first-person shooter in a destructible voxel world. ([Clients](https://github.com/yvt/openspades)) `GPL-3.0``Python/C++`
- [QuakeJS](https://github.com/begleysm/quakejs) - QuakeJS is a port of ioquake3 to Javascript that can be played in a browser. `MIT``Nodejs`
- [Quizmaster](https://github.com/nymanjens/quizmaster) - A web-app for conducting a quiz, including a page for players to enter their answers. `Apache-2.0``Scala`
- [Red Eclipse 2](https://redeclipse.net) - A FOSS Arena First-Person Shooter Similar to Unreal Tournament. ([Source Code](https://github.com/redeclipse/base)) `Zlib/MIT/CC-BY-SA-4.0``C/C++`
- [Red Eclipse 2](https://redeclipse.net) - A FOSS Arena First-Person Shooter Similar to Unreal Tournament. ([Source Code](https://github.com/redeclipse/base)) `Zlib/MIT/CC-BY-SA-4.0``C/C++/deb`
- [Romm](https://github.com/zurdi15/romm) `⚠` - RomM (Rom Manager) is a web based retro roms manager integrated with IGDB. `GPL-3.0``Docker`
- [The Battle for Wesnoth](https://github.com/wesnoth/wesnoth) - The Battle for Wesnoth is an Open Source, turn-based tactical strategy game with a high fantasy theme, featuring both singleplayer and online/hotseat multiplayer combat. `GPL-2.0``C++`
- [The Battle for Wesnoth](https://github.com/wesnoth/wesnoth) - The Battle for Wesnoth is an Open Source, turn-based tactical strategy game with a high fantasy theme, featuring both singleplayer and online/hotseat multiplayer combat. `GPL-2.0``C++/deb`
- [Veloren](https://veloren.net/) - Multiplayer RPG. Open-source game inspired by Cube World, Legend of Zelda, Dwarf Fortress and Minecraft. ([Source Code](https://gitlab.com/veloren/veloren)) `GPL-3.0``Rust`
- [Word Mastermind](https://github.com/clupasq/word-mastermind) - Wordle clone. A Mastermind-like game, but instead of colors you need to guess words. ([Demo](https://word-mastermind.glitch.me/)) `MIT``Nodejs`
- [Wordle](https://reactle.vercel.app/) - An Open Source Wordle game. Guess the Wordle in six tries. Each guess must be a valid five-letter word. ([Source Code](https://github.com/cwackerfuss/react-wordle)) `MIT``Nodejs`