There are 3 open-source alternatives to Mattermost in this directory. The most popular is Rocket.Chat with 42.2k GitHub stars, followed by Zulip(25.0k 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 | Zulip An open-source team chat that helps teams stay productive and focused. | 25.0k | Python | Apache License 2.0 |
| 3 | Signal-Server Backend server powering the Signal Private Messenger, ensuring secure, end-to-end encrypted messaging and calling across Android, Desktop, and iOS. | 10.2k | Java | GNU Affero General Public License v3.0 |
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 team chat that helps teams stay productive and focused.
Backend server powering the Signal Private Messenger, ensuring secure, end-to-end encrypted messaging and calling across Android, Desktop, and iOS.
The top three are Rocket.Chat(42.2k stars), Zulip(25.0k stars), Signal-Server(10.2k 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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