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Most buyers should pick Slack.
Choose Mattermost when self-hosting, private cloud or air-gapped deployment is a requirement, or when incident playbooks and operational workflows matter most. Choose Slack for a conventional team-chat workspace with published per-user pricing, paid-plan app integrations and AI features. Mattermost Entry is free but capped at 100 users and has limited history; commercial plans require custom quotes. Slack’s free plan limits history to 90 days. Overall, Slack is easier to price; Mattermost offers more deployment control.
01Side by side
| Mattermost | Slack | |
|---|---|---|
| Starting price | $0 Mattermost Entry | $0 Slack Free |
| Free plan | 100 users; 10,000-message channel history | 90-day history; up to 10 apps |
| Best for | Teams needing self-hosted or air-gapped operations | Teams wanting connected chat, apps and AI |
| Core strength | Deployment control and incident playbooks | Channels, integrations and AI tools |
| Learning curve | Not stated on the vendor's site | Not stated on the vendor's site |
| Integrations / data | Self-hosted, private-cloud and air-gapped options | Unlimited app integrations on paid plans |
| Team / seat costs | Paid plans: custom annual seat quotes | $7.25–$45/user/month, annual billing |
| Support | Premier Support add-on; price unpublished | Not specified on the vendor's site |
Mattermost Choose Mattermost if
- Choose Mattermost if you need self-hosted or air-gapped deployment.
- Choose Mattermost if operational playbooks and incident workflows are central.
- Choose Mattermost if you want control over data and deployment.
Slack Choose Slack if
- Choose Slack if you want published per-user plan prices.
- Choose Slack if your team relies on app integrations.
- Choose Slack if you want channels, huddles and AI in one workspace.
02Pricing compared
Slack is easier to price: its Pro plan is $8.75 per user monthly or $7.25 per user monthly with annual billing, according to the pricing page. Business+ is $18 monthly or $15 with annual billing; Enterprise+ lists an annual rate of $45 per user monthly. Slack Free includes 90 days of message history.
Mattermost Entry costs $0 for self-hosted teams, capped at 100 users, 10,000 messages of channel history, 1,000 board cards, five active playbook runs monthly and 250 agent queries monthly. Professional, Enterprise and Enterprise Advanced require custom quotes and prepaid annual seat subscriptions; monthly prices are not published. Mattermost also reports quarterly true-ups for commercial plans, while overage costs are not published. So the trade-off is clear: Slack publishes seat prices, while Mattermost’s paid cost requires a quote.
03Features and depth
Mattermost’s distinction is deployment control and operational tooling. Its homepage says it can run self-hosted, in private cloud or in air-gapped environments. Channels, threads and direct messages include permissions, retention and priority-message acknowledgements. Playbooks support incident response, change management and compliance with checklists, SLA timers and escalations. Boards provide kanban, table, calendar and gallery views alongside conversations.
Slack centers on a shared workspace for team communication and connected apps. Its feature set includes channels, huddles, Slack Connect for client and vendor conversations, and workflows for stand-ups, project updates and approvals. Slack also lists AI search, AI meeting notes in huddles and Slackbot, which coordinates work across connected apps and agents.
Both offer AI features, but the emphasis differs: Mattermost describes agents that can use a chosen LLM provider or self-hosted model, while Slack’s listed plans vary in AI access. Mattermost also supports server federation and partner-system interoperability; Slack’s listed collaboration option is Slack Connect.
04Ease of use and learning curve
For a conventional team-chat setup, Slack is the more straightforward fit on paper: its plans describe a workspace built around channels, apps, huddles and workflows, with published per-user prices. Our review scores Slack 7/10 for ease of use and Mattermost 6/10; those scores are not a measure of every team’s learning curve.
Mattermost offers more deployment choices, including self-hosted, private-cloud and air-gapped environments, plus playbooks, boards and server federation. Those options may suit teams with specific operational needs, but they also mean more choices to assess before settling on a setup. We would choose based on whether that control is necessary, rather than assuming either product will be easier for every team.
Questions people ask
Who is Slack's biggest competitor?
The published product information does not identify Slack’s biggest competitor or rank collaboration tools by market share. Mattermost is one alternative covered here, particularly for organizations that need self-hosting, private-cloud or air-gapped deployment, but the sources do not establish it as Slack’s biggest competitor.
Does Tesla use Mattermost?
The published sources do not say whether Tesla uses Mattermost. They describe Mattermost’s product and deployment options, but name no Tesla deployment or customer relationship. We can’t confirm Tesla’s use from this information.
Why don't people like Slack?
The published review describes Slack’s free plan as limited and says advanced AI costs more. Its Free plan includes 90 days of message history, while advanced AI is listed on Business+. Those limits may not suit every team, but the sources don’t establish broader reasons people dislike Slack.
Is Mattermost free if self-hosted?
Mattermost Entry is listed at $0 for small self-hosted teams, with limits: up to 100 users, 10,000-message channel history, 1,000 board cards, five active playbook runs per month and 250 agent queries per month. Commercial plans require custom quotes.