Mattermost.com
Depends
Confidence: Medium
Buy if you're a regulated, defense, or government team that must self-host chat and has ops staff to run it.
New check
Comparison
Mattermost.com vs Zulip
Mattermost.com and Zulip both land on Depends.
Zulip
Depends
Confidence: Medium
Buy if your distributed team or community drowns in chat noise and will commit to the topic-threading model.
| Compare | ||
|---|---|---|
| Verdict | Depends | Depends |
| Best for | Defense and government contractors | Distributed teams drowning in chat noise |
| Who it's not for | Small teams that just want a group chat | Teams wanting a drop-in Slack replacement with zero onboarding |
| Privacy | Active security program with bug bounty and routine scans, but several recent CVEs are disclosed, including an auth bypass.⁸ | Active security program (HackerOne disclosure, prompt releases), but multiple CVEs landed in 2025-26 including an authentication bypass.13 |
| Support quality | No support quality evidence found | No direct support-quality evidence found |
| Public sentiment | Engineers praise the self-hosted threading model while users report slow mobile apps, message-history paywalls, and shrinking free features.⁴ | Reviewers consistently praise Zulip's organized, threaded conversations and pricing while admitting an adjustment period versus Slack.15 |
| Biggest gotcha | Entry edition locks message history after 10,000 messages . older messages sit behind paid plans. | Self-hosters own updates: 2025-26 brought auth-bypass and info-disclosure CVEs13 |
Pick Mattermost.com when
- Defense and government contractors
- Regulated industries needing self-hosting
- DevOps and engineering teams
- Air-gapped or sovereign deployments
When Mattermost.com is not a fit
- Small teams that just want a group chat
- Companies with no sysadmin or DevOps staff
- Anyone expecting a durable free tier
- Mobile-first teams
Pick Zulip when
- Distributed teams drowning in chat noise
- Open-source communities
- Async-first remote orgs
- Buyers wanting self-hosting and data control
When Zulip is not a fit
- Teams wanting a drop-in Slack replacement with zero onboarding
- Small teams needing quick casual chat . threading is overkill
- Real-time social or gaming communities better served by Discord
- Self-hosters without time to patch security releases promptly
Sources
- Mattermost Pricingmattermost.comofficial
- Mattermost on GitHub (open source)github.comofficial
- Mattermost Security Updatesmattermost.comofficial
- Mattermost reviews on G2g2.comreview
- Mattermost on Trustpilottrustpilot.comreview
- Mattermost on Google Playplay.google.comreview
review
- CVE-2026-6339 auth bypass (SentinelOne)sentinelone.comsecurity
security
- Mattermost funding and ARR (GetLatka)getlatka.comnews
- Zulip plans and pricingzulip.comofficial
- Zulip security pagezulip.comsecurity
- CVE-2025-31478 - NVDnvd.nist.govsecurity
- Zulip Server 12.2 security releaseblog.zulip.comsecurity
- Zulip Reviews on G2g2.comreview
- Zulip Reviews on Capterracapterra.comreview