Mattermost vs Rocket.Chat
Both are alternatives to Slack. Here's how they stack up — verified facts, no spin.
Also searched as Rocket.Chat vs Mattermost — same comparison, one verdict.
Mattermost and Rocket.Chat are closely matched on ownership (88 vs 85) — this one comes down to pricing and to which trade-offs below you can live with.
Mattermost
TOP PICKSelf-hosted team chat built for security-conscious orgs.
Mattermost is an open-source, self-hostable Slack alternative with strong security and compliance features, popular with engineering and defense/regulated teams that need to own their data.
Rocket.Chat
MIT-licensed, highly customizable team communication.
Rocket.Chat is a permissively licensed (MIT) open-source communications platform you can self-host and reshape freely, with chat, voice, and omnichannel features.
Side by side
10 points of comparison, every one read from a verified field. Green marks the side that wins a row outright. A dash means we do not hold that fact — never that it is zero.
| Mattermost | Rocket.Chat | |
|---|---|---|
| Sovereignty ScoreOur transparent 0–100 composite for data ownership and exit cost. | 88 | 85 |
| Open source | Yes | Yes |
| Self-hostable | Yes | Yes |
| Local-first data | Yes | Yes |
| License | AGPL-3.0 | MIT |
| Pricing | Free self-host; paid Enterprise | Free self-host; paid cloud/enterprise |
| RAM to run it wellThe figure that actually matters, not the vendor's minimum. | 4 GB for a team of 50 with PostgreSQL on the same box | 6 GB with MongoDB on the same machine |
| Realistic running costWhat the box costs each month if you run it yourself. | $25–40/mo for a 50-person team | $35–55/mo for a small team |
| Setup timeHonest first-install estimate, not the marketing quickstart. | 2 hours | 2–3 hours |
| Ongoing maintenanceThe part nobody budgets for. | Moderate. Upgrades are well behaved; the database needs a real backup. | Active. MongoDB version compatibility is the recurring chore. |
Mattermost is Macrostack's recommended Slack alternative, so it's our pick here.
Weighing both against staying on Slack? Is Slack free? What it actually costs →
Mattermost
Strengths
- +Purpose-built self-hosted Slack replacement
- +Strong security/compliance story
- +Familiar channel UX
Trade-offs
- −You operate the server
- −Some features are Enterprise-only
Rocket.Chat
Strengths
- +Permissive MIT license
- +Very customizable and extensible
- +Omnichannel features
Trade-offs
- −Broad feature set can feel heavy
- −Some capabilities gated to paid tiers
Which one fits you
The trade-offs above, turned into a decision. Find the line that describes your team.
Choose Mattermost
if a lower exit cost matters more to you than any single feature, and purpose-built self-hosted Slack replacement.
Choose Rocket.Chat
if permissive MIT license.
Neither, yet
if both carry a real cost you should weigh first — you operate the server, and broad feature set can feel heavy. If either of those is a dealbreaker for your team, the shortlist is wrong rather than the choice.
What it takes to run these yourself
Real requirements and honest running costs, not the vendor quickstart.
Mattermost vs Rocket.Chat — common questions
Is Mattermost a better fit than Rocket.Chat for team chat?
It depends on what you are optimising for, and the honest split is this: Mattermost scores 88 to Rocket.Chat's 85 on data ownership and exit cost, so it is the safer choice if you care about being able to leave. Rocket.Chat earns its place on a different axis — permissive MIT license. Neither is a wrong answer for every team; the table above is the actual comparison.
What happens if we want to switch later?
Mattermost keeps its data local or in open formats, so leaving is an export rather than a negotiation. Rocket.Chat is still self-hostable, so the files stay on your server either way — but it is not local-first by design, so check what its export produces before you rely on it.
Can I self-host Mattermost or Rocket.Chat?
Both can be self-hosted. The difference is what it costs you in time rather than whether it is possible — see the setup and maintenance rows above.
Are Mattermost and Rocket.Chat both alternatives to Slack?
Yes — both appear in our Slack comparison, which is why they are worth putting side by side. People usually arrive here already having decided to move off Slack and now choosing between the two replacements, which is a narrower and much easier question.
More Slack head-to-heads
Related alternative guides
Facts verified 2026-07-04. Licenses and pricing change — spotted something out of date? That's a correction we want.