Mattermost
Free (self-hosted) / paid tiers
Slack
Free / from ~$8.75 per user/mo
Mattermost is an open-source, self-hostable team chat platform built for security-conscious organizations that want control. Slack is the polished, widely adopted chat platform with a huge app ecosystem. Mattermost wins on self-hosting and control; Slack wins on polish, ecosystem, and ease.
Pick Mattermost if you need self-hostable, open-source team chat with full data control and security.
Pick Slack if you want the most polished, widely adopted chat with the biggest app ecosystem.
Mattermost and Slack are both team chat platforms, but they appeal to different priorities. Mattermost is open source and self-hostable, so organizations that need data control, security, and compliance can run it on their own infrastructure, which is popular in regulated industries and engineering-heavy teams. Slack is the polished, widely adopted standard, with a delightful experience, the largest app ecosystem, and seamless integrations.
On price, Mattermost is free when self-hosted with paid tiers for enterprise features, while Slack has a free tier and paid plans from around $8.75 per user per month. The choice is mostly self-hosting and control (Mattermost) versus polish, ecosystem, and ease (Slack).
We compare self-hosting, open source, polish, integrations, and price.
| Quick facts | Mattermost | Slack |
|---|---|---|
| Open source / self-host | Best-in-class | No |
| Pricing | Free self-hosted / paid | Free / from ~$8.75/user/mo |
| Polish & ease | Good | Best-in-class |
| App ecosystem | Strong | Best-in-class |
| Best for | Control + security | Polish + ecosystem |
Each row reflects the feature on each product's current public release.
| Feature | M Mattermost | S Slack |
|---|---|---|
| Channels & messaging | Yes | Yes |
| Self-hosting | Best-in-class | No |
| Open-source codebase | Yes | No |
| Data control / compliance | Best-in-class | Strong |
| Polished experience | Good | Best-in-class |
| App / integration ecosystem | Strong | Best-in-class |
| Developer / DevOps tooling | Best-in-class | Strong |
| Free option | Self-hosted | Free tier |
Pricing and features change often. Always verify the current details on each product's official site. Last reviewed 2026-06-26.
Things neither product's marketing page leads with.
Mattermost gives you self-hosting and control, but its polish and ecosystem trail Slack.
Slack is the most polished with the biggest ecosystem, but it is cloud-only and cannot be self-hosted.
For control and security Mattermost wins; for polish and ecosystem Slack wins.
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