Top pick · highest health
Rocket.Chat
Communications platform that puts data protection first (alternative to Gitter.im and Slack).
DockerNodejsK8S
Communication - Custom Communication Systems
Open source alternatives to Slack
We track 9 open-source Slack alternatives, of which 7 currently score 70 or above on Repoly's GitHub health scale and 5 ship a Docker image. Rocket.Chat leads on health at 99/100 with 721 commits in the last 90 days; across all 9 projects you are choosing between Apache-2.0, EPL-2.0, GPL-3.0 and 2 other licences.
updated Oct 2026 9 alternatives best health 99 ★ 211k combined 3,486 commits / 90d 5 with Docker
Top picks to replace Slack
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Healthiest
Health 99/100: 721 commits in 90 days, latest release 8.9.0, Docker image available.
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Most active
808 commits in the last 90 days, more than any other option here.
Showing 9 of 9 tools
All 9 Slack alternatives, ranked by health
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Mattermost
Platform for secure collaboration across the entire software development lifecycle, can be integrated with Gitlab (alternative to Slack).
DockerGoK8S -
Chatwoot
Customer communication platform (alternative to Intercom and Zendesk).
DockerRubyK8S -
Huly
All-in-one project management platform (alternative to Linear, Jira, Slack, Notion, Motion).
DockerK8SNodejs -
Zulip
Zulip is a powerful, open source group chat application.
Python -
Element
Fully-featured Matrix client for Web, iOS & Android.
Nodejs -
Tinode
Instant messaging platform. Backend in Go. Clients: Swift iOS, Java Android, JS webapp, scriptable command line; chatbots.
Go -
Colanode
Collaboration suite with real-time messaging, rich text pages, file management, and dynamic databases - built for offline work (alternative to Slack, Notion).
DockerK8S -
Virola Messenger
Instant messaging and collaboration tool with private and group chat rooms, continuous voice and video meetings, files sharing, issue tracking with integrated task board (alternative to Slack).
C++
Slack alternatives compared
Rocket.Chat edges Mattermost 99 to 98. Rocket.Chat also has the largest following, at 46k stars.
The most recent release is Element v1.12.33, published 3 days ago. None of the measured options scores under 40. By stack, Nodejs (3), Go (2) and C++ (1) are the most common. Rocket.Chat, Zulip, Element and 1 more are permissively licensed; Huly and Tinode are copyleft. Mattermost, Chatwoot and Virola Messenger are source-available rather than open source, which limits commercial reuse. Virola Messenger is not hosted on a forge Repoly can read, so it has no measured score yet.
| Tool | Health | Stars | Licence | Last commit | Docker |
|---|---|---|---|---|---|
| Rocket.Chat Steady at 99 since 11 Sep | 99 | 46k | MIT | today | Yes |
| Mattermost Steady at 98 since 11 Sep | 98 | 39k | ⊘ Proprietary | today | Yes |
| Chatwoot Steady at 98 since 11 Sep | 98 | 39k | ⊘ Proprietary | today | Yes |
| Huly Steady at 98 since 11 Sep, no release for 3 months | 98 | 28k | EPL-2.0 | yesterday | Yes |
| Zulip Steady at 88 since 11 Sep | 88 | 26k | Apache-2.0 | today | No |
| Element | 87 | 14k | Apache-2.0 | today | No |
| Tinode | 87 | 14k | GPL-3.0 | 5 days ago | No |
| Colanode | 58 | 5.2k | Apache-2.0 | 7 months ago | Yes |
| Virola Messenger | 10 | 0 | ⊘ Proprietary | unknown | No |
Slack alternatives: common questions
What is the most maintained open source alternative to Slack?
Rocket.Chat scores highest at 99/100, with 721 commits in the last 90 days, 46k stars on GitHub and its latest release (8.9.0) published 25 days ago. Zulip has the most raw commit activity at 808 commits in 90 days.
Which Slack alternatives use a permissive licence?
4 of 9 are permissively licensed (MIT, Apache, BSD or similar): Rocket.Chat (MIT), Zulip (Apache-2.0), Element (Apache-2.0), Colanode (Apache-2.0). 2 use copyleft licences such as GPL or AGPL, which require you to publish changes if you distribute a modified version.
Which Slack alternatives run in Docker?
5 of 9 publish a Docker image or Compose file: Rocket.Chat, Mattermost, Chatwoot, Huly, Colanode. Docker support contributes 10 of the 100 available health points, because it is the clearest signal that self-hosting is a supported path rather than an afterthought.
Is Rocket.Chat or Mattermost the better Slack alternative?
On measured health Rocket.Chat leads, 99 to 98. Rocket.Chat has 721 commits in 90 days, 46k stars and 8.9.0 from 25 days ago; Mattermost has 716 commits in 90 days, 39k stars and v12.0.1 from 8 days ago. Rocket.Chat is ahead or level on every term Repoly measures.
Are the Slack alternatives still maintained?
7 of the 8 measured options score 70 or above. Colanode had no commits in the last 90 days. None scores under 40.
What languages are the Slack alternatives written in?
Nodejs: Rocket.Chat, Huly and Element. Go: Mattermost and Tinode. C++: Virola Messenger. The stack matters if you plan to extend or patch the tool yourself.
