Rocket.Chat is an open-source communications platform for secure team messaging, channels, DMs, voice/video, integrations, and customer omnichannel support.

46k stars13.8k forkslast commit Actively maintained
Cloud communication platform providing organized servers with persistent text channels, voice and video calls, direct messaging, screen sharing, roles and permissions, moderation tools, and integrations for communities, gaming groups and teams.
Rocket.Chat is an open-source communications platform for secure team messaging, channels, DMs, voice/video, integrations, and customer omnichannel support.

46k stars13.8k forkslast commit Actively maintained
Open-source, self-hosted messaging platform for secure team collaboration with real-time chat, audio calls, screen sharing, and integrations.

38.9k stars8.9k forkslast commit Actively maintained
Open-source team chat server with topic-based threading for focused, asynchronous, and real-time communication in distributed teams.

25.8k stars10.1k forksApache-2.0last commit Actively maintained
Open-source, decentralized messaging network built on a Haskell core with Kotlin Multiplatform and native iOS clients; end-to-end encrypted messaging without user IDs.

19.3k stars1.4k forksAGPL-3.0last commit Actively maintained
NodeBB is a modern forum platform with real-time discussions, built-in chat, SSO options, plugins, and flexible theming, backed by Redis, MongoDB, or PostgreSQL.

15.2k stars3k forksGPL-3.0last commit Actively maintained
Tinode is an open source instant messaging platform with a Go backend, web/mobile clients, JSON WebSocket and gRPC APIs, and support for one-to-one and group chat.

13.5k stars2.1k forksGPL-3.0last commit Actively maintained
Element is a Matrix client for secure team messaging and collaboration, offering end-to-end encrypted chats and calls with interoperability across the Matrix network.

13.4k stars2.7k forksAGPL-3.0last commit Actively maintained
BigBlueButton is an open-source virtual classroom and web conferencing platform with real-time audio/video, screen sharing, whiteboards, breakout rooms, polling, and recordings.

9.2k stars6k forksLGPL-3.0last commit Actively maintained
Spacebar is an open source, self-hostable Discord-compatible communication platform with text chat, voice, and video, designed to work with existing clients and bots.

6.7k stars222 forksAGPL-3.0last commit Actively maintained
Open-source, local-first Slack and Notion alternative combining team chat, rich docs, databases, and file management with offline-first sync and self-hosting.

5k stars314 forksApache-2.0last commit Actively maintained
Synapse is a Matrix homeserver implementation for running federated, secure real-time chat and collaboration on your own infrastructure.

4.6k stars587 forksAGPL-3.0last commit Actively maintained
Tailchat is an open source team chat and collaboration platform with a strong plugin system, bot integrations, multi-group workspaces, and RBAC permissions.

3.6k stars397 forksApache-2.0last commit Actively maintained
Ergo is a modern IRC server (ircd) written in Go, with integrated account management, history storage, bouncer-like features, and strong IRCv3 support.

3.3k stars242 forksMITlast commit Actively maintained
Converse.js is an open-source, client-side web XMPP/Jabber chat app that can run standalone or be embedded into sites, with group chat and OMEMO encryption.

3.3k stars832 forksMPL-2.0last commit Actively maintained
Stoat is an open-source, self-hostable chat platform for communities and teams, offering text channels, permissions, moderation tools, and a web app.

3.3k stars383 forkslast commit Actively maintained
Openfire is an open source XMPP (Jabber) server for real-time messaging and collaboration, with a web admin console and a plugin ecosystem.

3.1k stars1.4k forksApache-2.0last commit Actively maintained
Tox is a decentralized, peer-to-peer communication system for encrypted messaging, voice/video calls, screen sharing, and file transfers without central servers.

2.7k stars311 forksGPL-3.0last commit Actively maintained
Stoat (formerly Revolt) is an open-source chat platform for communities and teams with channels, direct messages, roles/permissions, moderation tools, and bot support.

2.6k stars296 forksAGPL-3.0last commit Actively maintained
Loomio is a collaborative decision-making tool for group discussions, proposals, and polls, helping teams make transparent decisions asynchronously with a clear record.

2.6k stars703 forksAGPL-3.0last commit Actively maintained
Open-source browser-based peer-to-peer chat with E2E encryption, ephemeral messages, video/audio, screen sharing, direct file transfer, and iframe embedding.

2.3k stars430 forksGPL-2.0last commit Actively maintained
Every option on this page is open source and free to run on your own hardware, so you own the data and there is no subscription to cancel. 20 of 20 shipped a commit in the last six months. Licences in this list: Apache-2.0, AGPL-3.0, GPL-3.0, LGPL-3.0, MIT. In exchange you take on hosting, backups and updates yourself.
Browse everything in Team Chat & Messaging.