Comparison

Mattermost.com vs Rocket.Chat

Mattermost.com and Rocket.Chat both land on Depends.

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.

Depends

Confidence: Medium

Buy if you're a government, defense, or regulated organization needing air-gapped, sovereign messaging with RBAC and E2EE.

Mattermost.com versus Rocket.Chat
Compare	Mattermost.com	Rocket.Chat
Verdict	Depends	Depends
Best for	Defense and government contractors	Government and defense agencies
Who it's not for	Small teams that just want a group chat	Small teams wanting a simple Slack replacement
Privacy	Active security program with bug bounty and routine scans, but several recent CVEs are disclosed, including an auth bypass.^⁸	Strong posture: end-to-end encryption, RBAC, air-gapped deployment, WCAG 2.1 AA conformance; one published CVE.
Support quality	No support quality evidence found	No evidence in sources reviewed
Public sentiment	Engineers praise the self-hosted threading model while users report slow mobile apps, message-history paywalls, and shrinking free features.^⁴	Users average ~4.3/5, praising solid chat, channels, and document sharing while criticizing search and Slack-parity gaps.¹⁵
Biggest gotcha	Entry edition locks message history after 10,000 messages . older messages sit behind paid plans.	Most tier pricing is hidden behind 'contact sales' . no public numbers in sources¹²