Best Open-Source Communication Apps
The ranking highlights two open-source communication apps for teams, ordered by GitHub stars. Mattermost leads with 2,246 stars, offering version 6.2.2 under an Apache-2.0 license. Rocket.Chat follows with 1,691 stars, running version 4.14.1 with an MIT license. Both support Linux, macOS, and Windows for self-hosted collaboration.
These apps provide chat and team coordination without proprietary dependencies. Mattermost and Rocket.Chat enable organizations to deploy secure, customizable platforms. Their GitHub activity reflects active development and community engagement. The ranking focuses on technical specifics like licenses and compatibility.
| # | App | Stars | License |
|---|---|---|---|
| 1 | Mattermost | 2.2k | Apache-2.0 |
| 2 | Rocket.Chat | 1.7k | MIT |
Mattermost is a desktop application for team communication, available on Windows, Mac, and Linux. It provides messaging and collaboration features for organizations.
Rocket.Chat is a secure communication platform designed for mission-critical operations. It provides encrypted messaging and collaboration tools for teams.
Frequently asked questions
- What is the top pick in “Best Open-Source Communication Apps”?
- Mattermost currently leads this list, which is ordered by GitHub stars among the 2 open-source options we track.
- Are these apps free?
- Yes. Every app on this list is free and open-source. Download links point to each project's official release.
- How is this ranking decided?
- The order reflects GitHub stars, a public measure of popularity. Data is pulled from official sources and last refreshed on Jun 26, 2026. We don't accept payment for placement.
How we rank:entries are ordered by GitHub stars, a public popularity signal. Versions, licenses and platform support are read from official release feeds. We don't accept payment for inclusion or position. Supported platforms reflect the latest release (Linux, macOS, Windows).