Mattermost vs Slack Comparison
Compare Mattermost vs Slack features, pricing, and more.
Last updated: November 2026
Mattermost
6.7/10
Self-hostable, open-source team messaging and workflow platform with playbooks, kanban boards and AI agents, built for security-conscious and regulated organizations.
Slack
7.1/10
Slack is a channel-based messaging platform from Salesforce, with Lists, canvases, huddles and Workflow Builder for team coordination and light task tracking.
Feature-by-Feature Comparison
| Feature | | |
|---|---|---|
| Scores | ||
| Overall Rating | 6.7/10 | 7.1/10 |
| Integration | 7/10 | 10/10 |
| Analytics | 3/10 | 3/10 |
| Customization | 8/10 | 7/10 |
| Ease of Use | 6/10 | 7/10 |
| Support | 6/10 | 6/10 |
| Cost | 5/10 | 5/10 |
| Scalability | 9/10 | 9/10 |
| Security | 10/10 | 9/10 |
| Pricing | ||
| Free plan | Yes | Yes |
| Cheapest paid plan | $10/user/mo Professional | €8/user/mo Pro |
| Estimated cost for 10 users | Free Team Edition | Free Free |
| Features | ||
| Team messaging | ||
| File sharing | ||
| Client collaboration | ||
| App integrations | ||
| Task lists | ||
| Workflow automation | ||
| Kanban boards | ||
| Collaboration tools | ||
| Docs | Not listed | |
| Spreadsheet interface | Not listed | |
| Gantt charts | Not listed | |
| Task management | Not listed | |
| Time tracking | Not listed | |
Mattermost vs Slack cost by team size
| Team size | Mattermost | Slack |
|---|---|---|
| 1 user | FreeTeam Edition | FreeFree |
| 5 users | FreeTeam Edition | FreeFree |
| 10 users | FreeTeam Edition | FreeFree |
| 25 users | FreeTeam Edition | FreeFree |
| 50 users | FreeTeam Edition | FreeFree |
The plan that fits each team size, billed monthly, before add-ons and usage charges. Each cost opens that tool's pricing calculator for the team size.
Which One Should You Choose?
Why choose Mattermost
- Higher Customization score (8/10 vs 7/10)
- Higher Security score (10/10 vs 9/10)
- Better fit for government (9/10 vs 6/10)
Why choose Slack
- Higher Integration score (10/10 vs 7/10)
- Higher Ease of Use score (7/10 vs 6/10)
- Better fit for small business (8/10 vs 4/10)
- Better fit for startups (8/10 vs 5/10)
Pros & Cons
Mattermost
Pros
- Can be fully self-hosted or air-gapped, which suits defense, government and regulated industries
- Enterprise tiers include strong compliance tooling: FIPS 140-3 builds, legal hold, compliance export and granular RBAC
- Playbooks give incident and DevOps teams repeatable checklists with automated triggers inside chat
- Built-in Jira, GitHub and GitLab integrations, plus an open API for custom bots
- Open-source core under MIT and AGPL licenses avoids full vendor lock-in
Cons
- The Boards kanban plugin is in maintenance mode and has been removed from the in-product marketplace
- Since v11 the free Entry plan shows only the last 10,000 messages and Team Edition is capped at 250 users, which drew community criticism
- The vendor publishes no prices, licenses are annual prepaid only, and every server needs its own license
- No Gantt charts, time tracking or project reporting, so it cannot replace a dedicated project management tool
- Self-hosting requires admin time and server upkeep
Slack
Pros
- The app ecosystem is very large, and tools such as ClickUp, Notion, HubSpot and Clockify can post updates into channels.
- Slack Connect lets teams work in shared channels with up to 250 outside organizations on paid plans.
- Compliance coverage is broad, including ISO 27001, SOC 2 Type II, FedRAMP Moderate and HIPAA configurability.
- Lists add table and board layouts with assignees, due dates and subtasks, without leaving chat.
- Workflow Builder automates routine requests and approvals without code.
Cons
- There are no native Gantt charts, dependencies, time tracking or portfolio reporting, so Slack doesn't replace a dedicated PM tool.
- Frequent notifications and busy channels can interrupt focus, a common complaint in reviews.
- The free plan keeps only 90 days of message history and allows 10 apps.
- Advanced AI features require Business+ or above, and per-user costs add up as teams grow.
- Reviewers report that finding older messages through search can be difficult.
Not sold on either?
Frequently Asked Questions
Slack scores higher on our AI Software criteria: 7.1/10 against 6.7/10 for Mattermost. The largest gap is in Integration: 7/10 for Mattermost and 10/10 for Slack.
Yes, both Mattermost and Slack have a free plan.
Slack is the better fit for small business: we rate it 8/10 for them, against 4/10 for Mattermost.
