mattermost.com
Self-hosted team chat
Open-source messaging for teams: channels, threads, calls and integrations, on your own server or theirs.
Free alternative to Slack
| Resource | Pricing | Type | Licence | Platforms | Popularity | Last commit | Link |
|---|---|---|---|---|---|---|---|
| Mattermost | Open source | Tool | — | web | ★ 39k | 4 Oct 2026 | ✓ |
| Plane | Open source | Tool | AGPL-3.0 | web | ★ 60k | 1 Oct 2026 | ✓ |
| Formbricks | Open source | Tool | — | self-hosted | ★ 13k | 3 Oct 2026 | ✓ |
| BigBlueButton | Open source | Tool | LGPL-3.0 | web | ★ 9.2k | 3 Oct 2026 | ✓ |
| Anytype | Free | Tool | — | self-hosted | ★ 8.9k | 3 Oct 2026 | ✓ |
| Monica | Open source | Service | — | web | ★ 1.1k | — | ✓ |
| Rocket.Chat | Open source | Tool | — | web | ★ 46k | 3 Oct 2026 | ✓ |
Open-source project tracking
Open-source surveys and forms
Open-source virtual classroom
Local-first, encrypted workspace
Open-source CRM to manage friends and family
Open-source team and customer chat
