Comparison

Rocket.Chat vs Mattermost.com

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

Rocket.Chat

Depends

Confidence: Medium

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

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.

Rocket.Chat versus Mattermost.com
Compare	Rocket.Chat	Mattermost.com
Verdict	Depends	Depends
Best for	Government and defense agencies	Defense and government contractors
Who it's not for	Small teams wanting a simple Slack replacement	Small teams that just want a group chat
Privacy	Strong posture: end-to-end encryption, RBAC, air-gapped deployment, WCAG 2.1 AA conformance; one published CVE.^⁹	Active security program with bug bounty and routine scans, but several recent CVEs are disclosed, including an auth bypass.
Support quality	No evidence in sources reviewed	No support quality evidence found
Public sentiment	Users average ~4.3/5, praising solid chat, channels, and document sharing while criticizing search and Slack-parity gaps.^⁵	Engineers praise the self-hosted threading model while users report slow mobile apps, message-history paywalls, and shrinking free features.¹⁴
Biggest gotcha	Most tier pricing is hidden behind 'contact sales' . no public numbers in sources^²	Entry edition locks message history after 10,000 messages . older messages sit behind paid plans.