- [Freenet](https://freenetproject.org/index.html) - Anonymously share files, browse and publish "freesites" (web sites accessible only through Freenet) and chat on forums. ([Source Code](https://github.com/freenet/fred)) `GPL-2.0``Java`
- [Friends](http://moose-team.github.io/friends/) - P2P chat powered by the web. ([Source Code](https://github.com/moose-team/friends)) `MIT``Nodejs`
- [Gotify](https://gotify.net/) - Self-hosted notification server with Android and CLI clients, similar to PushBullet. ([Source Code](https://github.com/gotify/server), [Clients](https://github.com/gotify/android)) `MIT``Go`
- [Hawkpost](https://hawkpost.co) - HawkPost is a web app that lets you create unique links that you can share with a person that desires to send you important information but doesn't know how to encrypt it. The message is encrypted in their browser and sent to your email address. ([Source Code](https://github.com/whitesmith/hawkpost)) `MIT``Python`
- [Jami](https://jami.net/) - Free and universal communication platform which preserves the user's privacy and freedoms (formerly GNU Ring). ([Source Code](https://git.ring.cx/savoirfairelinux/ring-project)) `GPL-3.0``C++`
- [Jitsi Meet](https://jitsi.org/Projects/JitsiMeet) - Jitsi Meet is an OpenSource (MIT) WebRTC Javascript application that uses Jitsi Videobridge to provide high quality, scalable video conferences. ([Source Code](https://github.com/jitsi/jitsi-meet)) `MIT``Javascript`
- [Jitsi Video Bridge](https://jitsi.org/Projects/JitsiVideobridge) - WebRTC compatible Selective Forwarding Unit (SFU) that allows for multiuser video communication. ([Source Code](https://github.com/jitsi/jitsi-videobridge)) `Apache-2.0``Java`
- [Kandan](http://getkandan.com/) - Kandan is an Open Source Alternative to HipChat. ([Source Code](https://github.com/kandanapp/kandan)) `AGPL-3.0``Ruby`
@ -290,9 +292,9 @@ _CalDAV or CardDAV web-based clients._
- [Mibew](https://mibew.org) - Mibew Messenger is an open-source live support application written in PHP and MySQL. It enables one-on-one chat assistance in real-time directly from your website. ([Demo](https://mibew.org/demo2), [Source Code](https://github.com/Mibew/mibew)) `Apache-2.0``PHP`
- [Node-Chat](https://github.com/IgorAntun/node-chat) - Not-so-basic open-source chat with admin features. `MIT``Nodejs`
- [OTS](https://ots.fyi/) - One-Time-Secret sharing platform with a symmetric 256bit AES encryption in the browser. ([Source Code](https://github.com/Luzifer/ots)) `Apache-2.0``Go`
- [Rallly](http://rallly.co) - Rallly is a free collaborative scheduling service. ([Source Code](https://github.com/lukevella/Rallly)) `CC-BY-SA-4.0``Nodejs`
- [RetroShare](http://retroshare.org) - Secured and decentralized communication system. Offers decentralized chat, forums, messaging, file transfer. ([Source Code](https://github.com/RetroShare/RetroShare)) `GPL-2.0``С++`
- [Jami](https://jami.net/) - Free and universal communication platform which preserves the user's privacy and freedoms (formerly GNU Ring). ([Source Code](https://git.ring.cx/savoirfairelinux/ring-project)) `GPL-3.0``C++`
- [Rocket.Chat](https://rocket.chat/) - Teamchat solution similar to Gitter.im or Slack. ([Source Code](https://github.com/RocketChat/Rocket.Chat)) `MIT``Nodejs`
- [Spectrum 2](http://spectrum.im/) - Spectrum 2 is an open source instant messaging transport. It allows users to chat together even when they are using different IM networks. ([Source Code](https://github.com/hanzz/spectrum2)) `GPL-3.0``C++`
- [Spreed](https://www.spreed.me/) - WebRTC audio/video calls, conferencing server, and web client. ([Source Code](https://github.com/strukturag/spreed-webrtc)) `AGPL-3.0``Go`