Self-Hosted Slack Alternatives (Open Source)

These self-hosted Slack alternatives keep team chat history on servers you control. Slack's free plan keeps 90 days of message history, and Pro is listed at $8.75 per user per month when paying monthly (Slack pricing, checked 2026-10-26; promotional discounts may apply). Compare the picks below, then try one with your team.

Compare the top picks

Swap Slack for a stack you control. Compare Mattermost, Rocket.Chat, Zulip, Element on Matrix, Stoat (formerly Revolt) and Campfire, with licenses checked in each repo and self-host notes.

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Quick comparison

NameLicenseLanguageDocker?Last commit
MattermostAGPL-3.0Go / TypeScriptYes2026-10-26
Rocket.ChatMITTypeScript / JavaScriptYes2026-10-26
ZulipApache-2.0Python / TypeScriptYes2026-10-26
Element + Synapse (Matrix)AGPL-3.0Python / TypeScriptYes2026-10-26
Stoat (formerly Revolt)AGPL-3.0Rust / TypeScriptYes2026-10-07
Campfire (ONCE)MITRubyYes2026-10-24

License, stars and last commit checked against the GitHub API and repo files on 2026-10-26.

Listings

Mattermost

Secure team messaging built for self-host and compliance

AGPL-3.0 · OSIGo / TypeScriptDockerHosted option★ 39,437 as of 2026-10-26

Compiled binaries MIT; source AGPL-3.0 or commercial. Enterprise plugins/features source-available.

Pros
  • Enterprise-ready self-host with strong admin controls
  • Slack-familiar UX for teams
Cons
  • Enterprise features need commercial license
  • Heavier ops than lighter chat apps
WebsiteSourceDeploy on RepoCloud

Last commit (default branch): 2026-10-26 · Last verified: 2026-10-26

Rocket.Chat

Open-source communications platform for team chat and omnichannel

MIT · OSITypeScript / JavaScriptDockerHosted option★ 46,331 as of 2026-10-26

Core MIT; ee/ enterprise directories under separate commercial license.

Pros
  • MIT core with large feature surface
  • Omnichannel / integrations beyond pure Slack clone
Cons
  • Resource-heavy MongoDB stack
  • EE features gated
WebsiteSourceDeploy on RepoCloud

Last commit (default branch): 2026-10-26 · Last verified: 2026-10-26

Zulip

Team chat organized by topics — async-friendly Slack alternative

Apache-2.0 · OSIPython / TypeScriptDockerHosted option★ 26,116 as of 2026-10-26

Fully Apache-2.0 OSI open source.

Pros
  • Topic threading uniquely good for async teams
  • Clear Apache-2.0 license
Cons
  • UX learning curve vs channel-only Slack
  • Self-host prefers Debian/Ubuntu installer
WebsiteSourceDeploy on RepoCloud

Last commit (default branch): 2026-10-26 · Last verified: 2026-10-26

Element + Synapse (Matrix)

Decentralized, E2EE team chat via the Matrix protocol

AGPL-3.0 · OSIPython / TypeScriptDockerHosted option★ 4,737 as of 2026-10-26

Synapse AGPL-3.0 (or Element commercial). Element Web separate repo. Prefer Element Server Suite Community for packaged deploy.

Pros
  • True federation and E2EE
  • Open protocol (Matrix) — not a single-vendor lock-in
Cons
  • Homeserver ops more complex than Mattermost
  • Client + server are separate products to run
WebsiteSourceDeploy on RepoCloud

Last commit (default branch): 2026-10-26 · Last verified: 2026-10-26

Stoat (formerly Revolt)

Open-source Discord/Slack-style chat you can self-host

AGPL-3.0 · OSIRust / TypeScriptDockerHosted option★ 2,677 as of 2026-10-26

Rebranded from Revolt to Stoat. Self-host repo AGPL-3.0. Older revoltchat/* repos may still appear in search.

Pros
  • Modern Discord-like UX with Docker Compose
  • AGPL self-host stack
Cons
  • Younger / smaller ecosystem than Mattermost/Zulip
  • Brand rename Revolt→Stoat can confuse docs
WebsiteSourceDeploy on RepoCloud

Last commit (default branch): 2026-10-07 · Last verified: 2026-10-26

Campfire (ONCE)

Simple self-hosted group chat from 37signals / Basecamp

MIT · OSIRubyDocker★ 4,803 as of 2026-10-26

MIT open source (Once Campfire). Confirm once.com commercial packaging vs GitHub MIT repo for your use case.

Pros
  • Intentionally simple — less Slack bloat
  • MIT license on once-campfire
Cons
  • Fewer integrations than Mattermost/Rocket.Chat
  • Opinionated Once packaging model
WebsiteSource

Last commit (default branch): 2026-10-24 · Last verified: 2026-10-26

How to choose

FAQ

Is Stoat the same as Revolt?

Yes. The project rebranded from Revolt to Stoat. Prefer current stoat.chat / stoatchat links over old Revolt bookmarks.

Is Campfire fully open source?

The basecamp/once-campfire GitHub repo is MIT licensed.

Why no helpdesk tools here?

SelfHostSwap deliberately excludes Zendesk/Gorgias/Intercom-style customer-support suites. That is a different product niche.

“Deploy on RepoCloud” buttons appear only where RepoCloud has a page for that app (5 of 6 listings here). “Website” and “Source” links are not affiliate links.

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