Beeper
Automattic
Single inbox that bridges WhatsApp, Telegram, Signal, Slack and other networks into one desktop chat list.
Windows · macOS · Linux
No known warnings · checked 23 Oct 2026
Mattermost
Mattermost, Inc.
FREEApache-2.0
Desktop client for Mattermost servers, letting a team run its own channel-based chat on its own infrastructure.
Links go to the official site. SoftHarbor hosts no downloads.
At a glance
- Developer
- Mattermost, Inc.
- Platforms
- Windows · macOS · Linux
- License
- Apache-2.0
- Tags
- self-hosted · channels · teams · multi-server
- Security
- No known warnings · checked 23 Oct 2026 · View scan
- Added
- 28 Jul 2026
More in Communication
FREE
Betterbird
Betterbird contributors
Thunderbird fork that ships extra fixes and features which have not been merged into the upstream release.
MPL-2.0Windows · macOS · Linux
No known warnings · checked 23 Oct 2026
Claws Mail
The Claws Mail team
Lightweight GTK email client that stores mail as plain files and adds features through a large plugin set.
GPL-3.0-or-laterWindows · Linux
No known warnings · checked 23 Oct 2026
Delta Chat
Delta Chat contributors
Chat app that sends messages over ordinary email accounts, encrypting them end to end where both sides support it.
GPL-3.0-or-laterWindows · macOS · Linux
No known warnings · checked 23 Oct 2026