• https://www.privacytools.io/software/real-time-communication/
• https://www.fsf.org/blogs/community/better-than-zoom-try-these-free-software-tools-for-staying-in-touch
• https://docs.google.com/spreadsheets/d/1-UlA4-tslROBDS9IqHalWVztqZo7uxlCeKPQ-8uoFOU/htmlview

IRC: Messaging services have become all the rage in office atmospheres, but nothing about Messenger or Slack is new. In fact, Slack (and its counterpart for video games, Discord) takes more than a few cues from the venerable Internet Relay Chat (IRC). IRC remains an enduring way to have a text-based chat in real-time, and as evidenced by Web clients like The Lounge, or desktop clients like Pidgin, it can be as stripped down or feature-rich as you like. For a true hacker experience, you can also log into IRC using Emacs.

• IRCHelp.org — Help for the mIRC Client
• HexChat
• mIRC: IRC Networks and Servers

• The Lounge
• KiwiIRC

• Quasseldroid IRC Client
• IRCCloud

• Raspberry Pi IRC Server: Setup your own Chat Network - Pi My Life Up
• https://ubuntu.com/tutorials/irc-server#1-overview
• Metronome IM - About the Project
• https://www.inspircd.org/
• https://github.com/ngircd/ngircd
• https://github.com/jrosdahl/miniircd - A single python file server. that is amazing

XMPP: If you've ever used “Jabber,” older iterations of Google Talk or Facebook Messenger, then you've used XMPP. XMPP is a flexible and extensible instant messaging protocol that's lately seen a resurgence from clients like Conversations.im and encryption schema like OMEMO. XMPP is the instant messaging method we prefer at the FSF when we need to discuss something privately, or in a secure group chat, as everything is sent through servers we control and encrypted against individual staff members' private key. Also, access to the FSF XMPP server is one of the many benefits of our associate membership program.

• https://404.city/

Windows

• https://gajim.org/
• Desktop - Dino. Communicating happiness.

Android

• Android client Conversations: the very last word in instant messaging

Web

• Converse (conversejs.org)
• Xabber for Web
• Movim – Responsive web-based cross-platform XMPP client

• Prosody
• ejabberd XMPP Server with MQTT Broker & SIP Service
• https://snikket.org/ - Interesting new project that is a wrapper around Prosody to help making it easier to install and run.

• Matrix.org
• https://element.io/blog/element-home/

• Element
• https://nova.chat/
• FluffyChat

• Synapse
  • https://linuxhandbook.com/install-matrix-synapse-docker/
  • https://cyberhost.uk/element-matrix-setup/
  • https://github.com/spantaleev/matrix-docker-ansible-deploy
• Dendrite - Next generation replacement
• https://conduit.rs/

• https://delta.chat/en/ - email based and very interesting
• https://jami.net/ - completely peer-to-peer
• https://threema.ch/en
• tox.chat
• https://safeswiss.com/
• Session
• https://www.anonymousmessenger.ly/
• https://adamant.im/

• Mumble
• Jitsi
• BigBlueButton - Open Source Web Conferencing

• Mumble: Mumble is a real-time, low latency program for hosting and joining audio conversations. Clients are available for every major operating system, and even large rooms tend not to put too much stress on the network. When it was time for us to go fully remote, the FSF staff turned to Mumble as a way to have that “in-office” feel, staying in touch in rooms dedicated to each of our teams and a general purpose “water cooler” room.
• Asterisk/SIP: When we give tours of the FSF office, people often think we're joking when we mention that even the FSF's conference phones run free software. But through Asterisk and our use of the SIP protocol, it's entirely true. Although it can be difficult to set up, it's worth mentioning that free software can manage your traditional phone lines. At the FSF, we transfer calls to digital extensions seamlessly with tools like Jami and Linphone.

Video calls and presentations

• Jitsi: Jitsi was a key part of LibrePlanet 2020's success. Providing video and voice calls through the browser via WebRTC, it also allows for presenters to share their screen in a similar way to Zoom. And unlike Zoom, it doesn't come with serious privacy violations or threats to user freedom. The connection between callers is direct and intuitive, but a central server is still required to coordinate callers and rooms. Some of these, like the Jitsi project's own “Jitsi Meet” server, recommend proprietary browser extensions and document sharing tools. If you're able, hosting your own instance is the most free and reliable method.
• Jami: While it's used at the FSF primarily for its SIP support, Jami (previously GNU Ring) is a solid communication client in its own right, allowing for distributed video calls, text chat, and screen sharing.
• OBS: Another much-used software program this LibrePlanet was OBS Studio. Illness, different timezones, or unforeseen travel were no match for the solutions that OBS Studio offered. It's a flexible tool for streaming video from multiple inputs to a Web source, whether that's combining your webcam with conference slides, or even your favorite free software game. At LibrePlanet, OBS allowed our remote speakers to record their presentations while speaking in one screen, and sharing audiovisual materials in a second window.

Long-form discussion