Mattermost
Secure team collaboration — messaging, playbooks, and integrations.
MIT-licensed alternative to Slack with channels, threads, webhooks, Jira/GitHub integrations, and Playbooks for incident response. Desktop and mobile apps.
Zulip
Topic-threaded team chat — keeps conversations organized at scale.
Zulip is an open-source team chat application built around topic-based threading, which keeps conversations organized in a way that channel-only tools like Slack or Rocket.Chat don't. Apache-2.0 licensed and self-hostable.
Element
Matrix-based team messaging — decentralized and end-to-end encrypted.
Element is an open-source, end-to-end encrypted collaboration client built on the decentralized Matrix protocol, so it can federate across independent servers rather than relying on one company's infrastructure. AGPL-3.0 licensed.
Fluxer
Discord-style chat for communities — messaging, voice, and video, self-hostable.
Fluxer is a free, open-source instant messaging and VoIP platform for friends, groups, and communities, styled after Discord. AGPL-3.0 licensed with self-hosting support.
Campfire
Simple self-hosted group chat from 37signals — one-time, MIT-licensed, no subscription.
Campfire is a simple, self-hosted group chat application from 37signals, released as open source under the MIT license in 2025. It's deliberately minimal — @mentions, DMs, rooms — with no recurring subscription.
Cinny
Elegant Matrix client — end-to-end encrypted, clean interface.
Cinny is an open-source Matrix client focused on a simple, elegant interface for end-to-end encrypted conversations. AGPL-3.0 licensed, it connects to any Matrix homeserver.
Stoat
Self-hostable Discord alternative (formerly Revolt) — servers, channels, voice.
Stoat (formerly Revolt) is an open-source, self-hostable group chat platform styled after Discord — servers, channels, voice, and moderation — built in the EU with no ads or data mining. Self-hosted components are AGPL-3.0 licensed.
Wire
End-to-end encrypted team collaboration — messaging, calls, EU-based.
Wire is an open-source, end-to-end encrypted collaboration platform for messaging, calls, and file sharing, aimed at organizations with strong security and compliance requirements. AGPL-3.0 licensed, based in the EU.
Quiet
Peer-to-peer team chat over Tor — no servers, no phone number, no metadata.
Quiet is an open-source, peer-to-peer team chat that syncs messages directly between devices over Tor, with no central server, no phone number, and no metadata collection. GPL-3.0 licensed.
Compare Rocket.Chat alternatives
Rocket.Chat is itself open source (MIT licensed) — a self-hosted, all-in-one communication platform with messaging, voice, video, and AI. If you're here, you're most likely comparing it against other open-source team and community chat tools rather than escaping a proprietary vendor.
Which one fits depends on your use case. For workplace team chat, Mattermost is the closest all-in-one alternative (strong on developer workflows and playbooks), while Zulip takes a different approach with topic-based threading that suits high-volume, asynchronous teams. If you want federation and default end-to-end encryption, Element and Cinny are built on the Matrix protocol, and Wire focuses specifically on end-to-end encryption and EU compliance. For a deliberately minimal option, Campfire (from 37signals) strips it back to rooms and DMs. For Discord-style community chat rather than workplace teams, Fluxer and Stoat are the closer fits, and Quiet takes a radically different peer-to-peer, no-server approach over Tor.
FAQ
Is there a free, open-source alternative to Rocket.Chat?
Rocket.Chat is already open source (MIT). If you want alternatives, Mattermost (MIT), Zulip (Apache-2.0), and Campfire (MIT) are all permissively licensed and free to self-host, alongside AGPL/GPL options like Element, Wire, and Quiet.
What's the best open-source alternative to Rocket.Chat for team chat?
Mattermost is the closest all-in-one match for workplace teams. Zulip is the better pick if your team is async-heavy and benefits from topic threading.
Which alternatives offer end-to-end encryption?
Element and Cinny (both Matrix-based) and Wire provide end-to-end encryption by default, whereas Rocket.Chat offers it as an option. Quiet goes further with a serverless, peer-to-peer design over Tor.
What are the top open-source alternatives to Rocket.Chat?
Browse all open-source alternatives to Rocket.Chat above, or explore the Communication & Community and Communication & Community categories.