Mattermost vs Slack: Pricing and Ratings Compared (2026)
Entry prices and free plans as read on each vendor's pricing page, and user ratings as published on review sites, for Mattermost and Slack side by side. This page compares data; it is not a hands-on review.
On the data: On the data below the two are close or not directly comparable, so we do not name a winner for this pair.
Short on time? Here's the quick answer
Based on published vendor pricing and features and on public review data, here's who should pick what:
Mattermost
Open-source team collaboration platform
Best for you if:
- • You want open source Slack alternative
Slack
Central hub for workplace communication and collaboration
Best for you if:
- • You want intuitive interface with low learning curve, most teams adopt it within days
| At a Glance | Mattermost | Slack |
|---|---|---|
Starts at | Free plan, paid from $10/user/mo, billed monthly Professional plan | Free plan, paid from $8.75/user/mo, billed yearly Pro plan |
Category | Communication Team Chat | Communication Team Chat |
Rating | 4.3/5 G2 4.3 · Capterra 4.4 · SourceForge 4.3 604 reviews | 4.2/5 G2 4.5 · Capterra 4.7 · TrustRadius 4.5 64,990 reviews |
Free plan | Yes | Yes |
Watch out for | n/a | 90-day message history on Free: after 90 days, old messages become invisible (not deleted, they return if you upgrade). This is the most common upgrade trigger and feels coercive for teams that relied on older unlimited history |
Choose Mattermost or Slack?
Choose Mattermost if
- You want open source Slack alternative
- You want self-hostable
Choose Slack if
- You want intuitive interface with low learning curve, most teams adopt it within days
- You want deepest third-party integration ecosystem of any team chat tool (2,600+ apps)
In-Depth Analysis
Mattermost
Open-source team collaboration platform
Mattermost's pricing is fair, offering a generous Free tier for small teams.
Strengths
- Pro: Open source Slack alternative
- Pro: Self-hostable
- Pro: Good for compliance
- Pro: No per-user cloud cost
- Pro: Customizable
Weaknesses
- Con: Less polished than Slack
- Con: Smaller integration library
- Con: Self-hosting required for best value
- Con: Learning curve
- Con: Community smaller
Key features
Slack
Central hub for workplace communication and collaboration
Slack is the default team messaging tool, and its pricing reflects that dominance.
Watch out
90-day message history on Free: after 90 days, old messages become invisible (not deleted, they return if you upgrade). This is the most common upgrade trigger and feels coercive for teams that relied on older unlimited history
Strengths
- Pro: Intuitive interface with low learning curve, most teams adopt it within days
- Pro: Deepest third-party integration ecosystem of any team chat tool (2,600+ apps)
- Pro: Slack Connect eliminates email chains with external partners via shared channels
- Pro: Powerful search across all messages, files, and connected apps from one bar
- Pro: Workflow Builder lets non-technical users automate routine processes
Weaknesses
- Con: Free plan limits message history and allows only a limited number of app integrations
- Con: Notification overload in large workspaces, channels can become noisy without discipline
- Con: Pricing adds up quickly for large teams
- Con: No built-in project management, still requires separate tools like Asana or Jira
- Con: Slack AI features require higher-tier plans, not available on all plans
Key features
Plans and prices: Mattermost vs Slack
| Tool | Plans and prices | Source |
|---|---|---|
| Mattermost |
| mattermost.com/pricing read Sep 30, 2026 |
| Slack |
| slack.com/pricing read Oct 11, 2026 |
Prices as read on each vendor's own pricing page on the date shown. Plans are listed per tool and are not matched against the other tool's plans: a plan name or price in one column says nothing about the same row in the other. Details on Mattermost pricing and Slack pricing.
Key Takeaways
Mattermost
- Choose if you want open-source team collaboration platform
Slack
- Choose if you want central hub for workplace communication and collaboration
What the data shows
On the data below the two are close or not directly comparable, so we do not name a winner for this pair.
- User ratings are within 0.2 points (4.3/5 from 604 reviews for Mattermost, 4.2/5 from 64,990 reviews for Slack).
- Entry prices are not ranked, they are charged on different bases: Mattermost $10/user/mo, billed monthly; Slack $8.75/user/mo, billed yearly.
- Both have a free plan.
Criteria: user rating (only above 20 reviews on both sides, gap of 0.2 or more), entry price (only on the same billing basis), free plan. How we rate
Frequently Asked Questions
How do Mattermost and Slack compare in 2026?
On the data below the two are close or not directly comparable, so we do not name a winner for this pair. User ratings are within 0.2 points (4.3/5 from 604 reviews for Mattermost, 4.2/5 from 64,990 reviews for Slack). Entry prices are not ranked, they are charged on different bases: Mattermost $10/user/mo, billed monthly; Slack $8.75/user/mo, billed yearly. Both have a free plan.
What are Mattermost and Slack used for?
Mattermost: Open-source team collaboration platform. Slack: Central hub for workplace communication and collaboration.
What does Mattermost cost vs Slack?
Mattermost's cheapest paid plan is Professional at $10/user/mo, billed monthly; it also has a free plan. Slack's cheapest paid plan is Pro at $8.75/user/mo, billed yearly; it also has a free plan. Prices read on the vendors' pricing pages, latest check Oct 11, 2026.
What's the main difference between Mattermost and Slack?
Mattermost's main strength: open source Slack alternative. Slack's main strength: intuitive interface with low learning curve, most teams adopt it within days.