Real-time team messaging without the per-seat tax. These open-source chat platforms offer channels, threads, video calls, and integrations — fully self-hosted.
Slack's $7.25/user/month pricing adds up fast, and its cloud-only model raises data residency concerns for regulated industries. Self-hosting a chat platform gives you complete message retention control, custom integrations, and zero per-seat costs at scale.
Mattermost is the most Slack-compatible open-source alternative. It offers channels, direct messages, threads, built-in bots, slash commands, webhooks, and a plugin system. The Community Edition is MIT-licensed and self-hostable — used by NASA, Uber, and the US DoD.
$docker run -d -p 8065:8065 mattermost/mattermost-team-editionRocket.Chat is a full Slack replacement with channels, video conferencing, file sharing, screen sharing, LiveChat, federation, and end-to-end encryption. It has a marketplace of apps and integrations. Used by 12M+ users in 150+ countries.
$docker run -d -p 3000:3000 rocketchat/rocket.chatZulip is a unique chat app where every message is part of a thread — making it dramatically easier to follow conversations. It's used by major open-source projects like Rust, Python, and ReadTheDocs. Fully self-hostable, with great keyboard navigation.
$docker run -d -p 80:80 zulip/docker-zulipMatrix is an open standard for decentralised communication. Element is its flagship client. Unlike Slack clones, Matrix is federated — servers can talk to each other, like email. It's the messaging backbone of the French government, German military, and FOSS communities.
$docker run -d -p 8080:80 vectorim/element-webRevolt is an open-source user-first chat platform built as an alternative to Discord. It features servers, channels, DMs, voice, video, and a growing bot ecosystem. The server software (Revolt Backend) is fully self-hostable under AGPL-3.0.
$docker-compose up -d