Communication

BigBlueButton is an open source web conferencing platform built specifically for online learning. Whiteboard, breakout rooms, polls, shared notes, and an LMS integration layer.

Element is the flagship client for the Matrix protocol. End-to-end encrypted messaging, voice, video, file sharing, bridges to Slack/Discord/Telegram. The secure Slack alternative.

Jami (formerly SFLphone) is a peer-to-peer communication platform. Encrypted text, voice, video, file transfer — no central server, no account required. The most private option.

Jitsi Meet is a fully encrypted, open source video conferencing platform. No account needed, share a link, start a meeting. The open source Zoom.

Mattermost is the chat platform used by the US Department of Defense, NASA, and 800+ enterprises. It focuses on technical workflows: deep GitHub/GitLab/Jira integration, runbooks, and high-trust compliance features. Self-hostable in Docker.

Mumble is the gold-standard open source VoIP for low-latency voice chat. Used by gaming communities, esports, and distributed teams. Self-hosted server, cross-platform client.

PeerTube is a federated, ActivityPub-based video hosting platform. Self-hostable, ad-free, no algorithm. Part of the Fediverse (like Mastodon for video).

Rocket.Chat is a full-featured team chat platform you can self-host. Channels, threads, DMs, voice, video, file sharing, integrations, bots, omnichannel customer support. Used by the US Navy, the Brazilian Air Force, and 12M+ users worldwide.