head to head · open source
Mattermost vs Signal
Mattermost has 39,093 GitHub stars, 9,000 forks, 1,012 open issues and last shipped yesterday. Signal has 29,352 stars, 6,888 forks, 498 open issues and last shipped yesterday. Mattermost leads on adoption by 33% (39,093 vs 29,352 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 | ★ 39K | ★ 29K |
| License | Custom / other | AGPL-3.0 |
| Written in | TypeScript | Kotlin |
| Last push | 2026-09-17 | 2026-09-17 |
| Forks | ⑂ 9.0K | ⑂ 6.9K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Mattermost if
- You weight community size — 39K 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 for teams that need secure chat, workflow automation, voice calling, screen sharing, and AI integration while keeping the deployment under their own control.
read the full Mattermost overview →
About Signal
Signal Android is a secure messaging application for Android devices that delivers private communication via end to end encryption. Developed by Signal Messenger, LLC, it operates within the broader Signal ecosystem, which includes official iOS and desktop clients. The app uses mobile data or Wi Fi to send and receive encrypted messages, voice calls, and video calls without relying on traditional SMS or telephony infrastructure.
read the full Signal overview →
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Frequently asked questions
Is Mattermost or Signal more popular?
Mattermost has 39,093 GitHub stars and Signal has 29,352. 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 (39,093 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.