Team Chat Apps · reliability comparison
Mattermost vs Slack: which is more reliable? (2026)
Mattermost is more reliable than Slack, scoring 100.0 vs 41.6 out of 100. Over the last 90 days Mattermost reported 0 incidents and Slack reported 8, with effective uptime of 100% and 97.89% respectively.
Data updated Nov 1, 2026 · How we score
| Metric | Mattermost | Slack |
|---|---|---|
| Reliability score | 100.0 | 41.6 |
| Rank (team chat apps) | #3 | #11 |
| Uptime (90 days) | 100% | 97.89% |
| Incidents (90 days) | 0 | 8 |
| Partial / major outages | 0 | 4 |
| Avg time to resolve | — | 15h 28m |
| Outages we detected | 0 | 0 |
| Transparency score | 100/100 | 100/100 |
Where Mattermost and Slack differ
- Mattermost reported no incidents in the last 90 days, while Slack reported 8.
- Slack had 4 partial or major outages, compared with 0 for Mattermost.
- Mattermost's longest incident on record lasted 21h 40m (Feb 26, 2026); Slack's lasted 3d (Aug 13, 2026).
90-day uptime
Mattermost
Slack
- No incidents
- Degraded
- Partial outage
- Major outage
- No data
Recent Mattermost incidents
No incidents reported by Mattermost in the last 90 days.
Recent Slack incidents
- Degraded performanceOct 22, 2026 · resolved (duration not published)
- Degraded performanceOct 14, 2026 · resolved in 6m
- Degraded performanceOct 9, 2026 · resolved (duration not published)
Incident: Slack for iOS closing unexpectedly when opening channels
- Partial outageOct 1, 2026 · resolved in 6h 20m
Incident: Free Plan Customers Are Experiencing Message Failures
- Partial outageSep 12, 2026 · resolved in 8h 56m
Incident: Some customers experiencing blurry image previews and download issues
- Degraded performanceSep 10, 2026 · resolved in 2h 40m
Incident: Trouble loading Workspace-level Apps & Workflows settings page is returning blank pages