Mattermost vs Slack
They differ on 5 of the 12 things buyers in this category actually ask about. Here is where, and what each one asks you to give up.
Mattermost
$10/seatOpen-source, self-hostable team chat built for regulated and air-gapped environments.
Strongest argument
Runs entirely inside your own infrastructure, including air-gapped
Biggest objection
Mobile and desktop clients trail the commercial alternatives in polish
Self-hosting is a real, ongoing operations cost — budget for the people, not just the licence.
Slack
$8.75/seatThe default team chat tool, with the deepest app directory of any.
Strongest argument
2,600+ integrations — almost anything you run already posts into it
Biggest objection
The free plan hides messages older than 90 days, which quietly makes history unusable
Per-seat price climbs steeply once you need compliance exports and unlimited history.
The differences that matter
Where they actually diverge
Only the rows where the two disagree. Everything they both do is listed below.
Cost
What each costs at 50 people
List price only. It ignores add-ons, seat minimums and the cost of the move itself — all of which routinely dwarf the difference below.
Prices are unverified estimates — useful for comparing orders of magnitude, not for budgeting. Confirm the current figure with the vendor before you commit to anything.
Common ground
What both of them do
These will not help you choose — which is exactly why they are worth knowing about before a vendor pitches one as a differentiator.
- Conversation modelChannels with threads
- Voice and videoBasic calls
- Retention and export controlsYes
- SAML single sign-onYes
- SOC 2Yes
- Public APIYes
- Native mobile appsYes
In full
Every pro and con, both sides
Mattermost
- Runs entirely inside your own infrastructure, including air-gapped
- Data residency is whatever you decide it is
- Slack-compatible enough that import and muscle memory both survive
- Mobile and desktop clients trail the commercial alternatives in polish
- Integration ecosystem is a fraction of Slack’s
- Upgrades and scaling are your problem once you self-host
Slack
- 2,600+ integrations — almost anything you run already posts into it
- Huddles turn a thread into a call without a scheduling step
- Search and retention controls that hold up at enterprise scale
- The free plan hides messages older than 90 days, which quietly makes history unusable
- Business+ pricing roughly doubles the bill the moment you need SAML or data exports
- Guest and connect seats add up fast when you work with agencies or clients
Questions
Mattermost vs Slack, answered
Mattermost or Slack — which is better?
Neither, in the abstract. Mattermost suits you if runs entirely inside your own infrastructure, including air-gapped matters most; Slack if 2,600+ integrations — almost anything you run already posts into it does. The honest trade-offs are: Mattermost — Self-hosting is a real, ongoing operations cost — budget for the people, not just the licence. Slack — Per-seat price climbs steeply once you need compliance exports and unlimited history.
Is Mattermost cheaper than Slack?
Slack is cheaper at 50 people — $10/seat/mo against $8.75/seat/mo, roughly $5,250 against $6,000 a year. That gap of about $750 is rarely the whole story though — add-ons, seat minimums and the cost of migrating routinely outweigh it.
Can we migrate from Mattermost to Slack?
Usually yes, and the difficulty depends on history, integrations and headcount far more than on the two products. Data export quality is the thing to check first: ask both vendors what you can take with you before you commit to either. Our questionnaire produces a scoped estimate for the move.
What else should we consider besides Mattermost and Slack?
In team communication the other credible options are Discord, Microsoft Teams, Zulip. Narrowing to two before you have written down your requirements is the most common way to end up with the wrong one.
Do not stop at two