Mattermost vs Spacebar
| Tagline | Open-source, self-hostable Slack alternative for secure team messaging and collaboration | Open-source, Discord-compatible chat backend you can self-host |
| Category | Team Chat & Collaboration | Team Chat & Collaboration |
| Replaces | Slack, Microsoft Teams, Discord | Discord |
| GitHub stars | 39k | 2.2k |
| Language | Go | TypeScript |
| License | MIT | AGPL-3.0 |
| Self-host difficulty | 3/5 Moderate | 4/5 Involved |
| Deploy options | One-Click Docker Docker Compose Kubernetes Manual | Docker Manual |
| Managed hosting | ||
| Last updated | yesterday | 3 days ago |
| View repo | View repo |
Where each falls short
The honest trade-offs — what you give up with each, versus the proprietary tools they replace.
Mattermost
- Many advanced features (LDAP/AD, SAML/SSO, compliance exports, high availability) are gated behind paid Enterprise tiers
- Search and message UX feel less polished than Slack
- Voice/video calling is more limited than Teams' full meetings stack
- Smaller third-party app/integration marketplace than Slack
Spacebar
- Still alpha/beta quality; not feature-complete or stable for production communities
- Voice/video support is incomplete or experimental
- Documentation and setup are rough and aimed at technical users
- No official polished first-party client; relies on Discord-compatible clients
Bottom line
Choose Mattermost if you want the lower-effort setup; choose Mattermost for the larger community and ecosystem. Mattermost has seen more recent development. Open each guide below for deploy steps and the full feature gap.
Mattermost
Open-source, self-hostable Slack alternative for secure team messaging and collaboration