head to head · open source
Mattermost vs Signal
Mattermost has 39,510 GitHub stars, 9,087 forks, 1,012 open issues and last shipped yesterday. Signal has 29,568 stars, 6,933 forks, 498 open issues and last shipped 4 days ago. Mattermost leads on adoption by 34% (39,510 vs 29,568 stars). Mattermost is written in TypeScript under a custom or non-standard licence; Signal is written in Kotlin under AGPL-3.0. Mattermost has attracted 23% as many forks as stars, Signal 23%. Mattermost was the more recently maintained of the two, and both are self-hostable with no licence fee.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| Mattermost | Signal | |
|---|---|---|
| GitHub stars | ★ 40K | ★ 30K |
| License | Custom / other | AGPL-3.0 |
| Written in | TypeScript | Kotlin |
| Last push | 2026-11-02 | 2026-10-30 |
| Forks | ⑂ 9.1K | ⑂ 6.9K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Mattermost if
- You weight community size — 40K stars and counting
- You want the Custom / other license terms
- Your stack matches TypeScript
- You value the larger contributor base for long-term maintenance
pick Signal if
- You want the Signal feature set and don't need the biggest community
- You prefer the AGPL-3.0 license terms
- Your stack matches Kotlin
- You evaluated both and Signal fits your workflow better
About Mattermost
Mattermost is an open core, self hosted collaboration platform that offers chat, workflow automation, voice calling, screen sharing, and AI integration. This repo is the primary source for core development on the Mattermost platform; it's written in Go and React, runs as a single Linux binary, and relies on PostgreSQL. A new compiled version is released under an MIT license every month on the 16th. Deploy Mattermost on premises, or try it for free in the cloud. Learn more about the following use cases with Mattermost: DevSecOps Incident Resolution IT Service Desk Other useful resources: Download and Install…
read the full Mattermost overview →
About Signal
Signal Android Signal is a simple, powerful, and secure messenger that uses your phone's data connection (WiFi/4G/5G) to communicate securely. Millions of people use Signal every day for free and instantaneous communication anywhere in the world. Send and receive high fidelity messages, participate in HD voice/video calls, and explore a growing set of new features that help you stay connected. Signal’s advanced privacy preserving technology is always enabled, so you can focus on sharing the moments that matter with the people who matter to you. Currently available on the Play Store and signal.org. Also available…
read the full Signal overview →
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Frequently asked questions
Is Mattermost or Signal more popular?
Mattermost has 39,510 GitHub stars and Signal has 29,568. Mattermost has the larger community by that measure.
Are Mattermost and Signal free?
Both are open source. Mattermost has no licence declared in this registry, and Signal is licensed under AGPL-3.0. Both are free to self-host.
What is the difference between Mattermost and Signal?
Mattermost is written in TypeScript and Signal in Kotlin. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Mattermost or Signal?
Choose Mattermost if you want the larger community (39,510 stars) or its Custom / other licence terms. Choose Signal if its feature set, stack or AGPL-3.0 licence fits better. Both are self-hostable.