There are 5 open-source alternatives to Slack in this directory. The most popular is Rocket.Chat with 42.2k GitHub stars, followed by Mattermost(36.2k stars). All are open source, free to use, and many can be self-hosted.
| # | Tool | Stars | Language | License |
|---|---|---|---|---|
| 1 | Rocket.Chat Rocket.Chat is a versatile open-source communication platform that prioritizes data protection and offers team collaboration, file sharing, and seamless integrations. | 42.2k | TypeScript | Other |
| 2 | Mattermost An open source platform for secure collaboration across the entire software development lifecycle. | 36.2k | TypeScript | Other |
| 3 | Platform Huly — All-in-One Project Management Platform offering integrated solutions for project management. It's an alternative to Linear, Jira, Slack, Notion, and Motion, streamlining workflows and improving productivity. | 25.3k | TypeScript | Eclipse Public License 2.0 |
| 4 | Zulip An open-source team chat that helps teams stay productive and focused. | 25.0k | Python | Apache License 2.0 |
| 5 | Spectrum Spectrum is a simple yet powerful platform for creating online communities, offering a seamless user experience for discussion and social engagement. | 10.8k | JavaScript | BSD 3-Clause "New" or "Revised" License |
Rocket.Chat is a versatile open-source communication platform that prioritizes data protection and offers team collaboration, file sharing, and seamless integrations.
An open source platform for secure collaboration across the entire software development lifecycle.
Huly — All-in-One Project Management Platform offering integrated solutions for project management. It's an alternative to Linear, Jira, Slack, Notion, and Motion, streamlining workflows and improving productivity.
An open-source team chat that helps teams stay productive and focused.
Spectrum is a simple yet powerful platform for creating online communities, offering a seamless user experience for discussion and social engagement.
The top three are Rocket.Chat(42.2k stars), Mattermost(36.2k stars), Platform(25.3k stars). All are open source and free to use.
Yes. Every tool listed here is open source and free to use in your own projects. Many can be self-hosted on your own infrastructure, which means no subscription fees and full control over your data.
Many of the alternatives listed are self-hostable. Each tool's page lists hosting details, system requirements, and licensing terms.
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