Mattermost vs Slack
Updated October 2026 · AppBreakup editorial
Mattermost
Open-source, self-hosted team messaging for secure environments.
The short answer
Slack suits companies that want hosted chat with the largest integration ecosystem and are comfortable with Salesforce holding their data. Mattermost suits security-conscious organisations, such as government, defence and finance teams, that need to self-host chat on their own infrastructure. The biggest difference is control: Mattermost is open source and runs where you choose, while Slack is a managed cloud service with less maintenance and more integrations.
Mattermost or Slack: our take
Day to day, the two feel alike: channels, direct messages and threads, and Mattermost's interface is close enough to Slack's that migrations are relatively easy. Slack adds audio huddles, Workflow Builder for automating requests and Slack Connect for sharing channels with partners and customers, plus thousands of integrations. Mattermost offers messaging, calls and workflow playbooks, and integrates with developer tools such as GitLab and Jira, but its integration catalogue is smaller than Slack's.
Data ownership is the core difference. Mattermost is designed to be self-hosted in your own data centre or private cloud, which lets organisations keep chat data where regulations require. That control comes with maintenance work: someone has to run, update and secure the servers. Slack is hosted by Slack, owned by Salesforce, and requires no infrastructure. On price, Mattermost has a free self-hosted edition, with enterprise plans adding compliance features, high availability and support. Slack has a free plan with limited message history, and paid plans unlock full history and admin controls at per-seat prices that rise quickly. Both have web, Windows, Mac, Linux, iOS and Android apps.
Choose Mattermost if you must keep messages on infrastructure you control, operate in regulated or air-gapped environments, or want an open-source tool you can inspect and extend. Choose Slack if you want chat that works immediately, need the broadest integrations, or collaborate with other companies in shared channels. Small teams without an operations person will usually find Slack's hosted service simpler; organisations with strict data rules often find Mattermost the only option that passes review.
Which should you pick?
Choose Mattermost if…
- Security-conscious organizations that must self-host chat
- You want open-source software
- You need to host it on your own servers
- You need Self-hosted, which Slack doesn't list
- Open source and self-hosted
Choose Slack if…
- Companies that want the largest integration ecosystem for chat
- Huge integration ecosystem
- Polished threads and huddles
About each app
What is Mattermost?
Mattermost is an open-source collaboration platform offering channel-based messaging, calls and workflow playbooks, designed to be self-hosted in your own data center or private cloud. It is popular with government, defense, finance and security teams that need control over where their data lives, and it integrates with developer tools such as GitLab and Jira. Teams can run the free self-hosted edition or buy enterprise plans for compliance features, high availability and support. Its interface will feel familiar to Slack users, which eases migration for teams moving away from hosted chat.
What is Slack?
Slack organizes team communication into channels by topic, project or team, alongside direct messages, threads and audio huddles. Thousands of integrations bring alerts and actions from other tools into conversations, and Workflow Builder automates routine requests. Slack Connect lets companies share channels with partners and customers. It is owned by Salesforce. The free plan limits how much message history you can see, which is a frequent reason small teams and communities look for alternatives, while paid plans unlock full history, more integrations and administration controls.
Side by side
| Attribute | Mattermost | Slack |
|---|---|---|
| Pricing | Open source | Free plan + paid |
| Open source | Yes | No |
| Self-hostable | Yes | No |
| Platforms | Web, Windows, macOS, Linux, iOS, Android, Self-hosted | Web, Windows, macOS, Linux, iOS, Android |
| Best for | Security-conscious organizations that must self-host chat | Companies that want the largest integration ecosystem for chat |
| Status | Active | Active |
Mattermost vs Slack pricing
Mattermost: open source
We couldn't verify Mattermost's plan details on its own site yet, so we don't list them.
Mattermost pricing pagePlatforms
| Platform | Mattermost | Slack |
|---|---|---|
| Web | ||
| Windows | ||
| macOS | ||
| Linux | ||
| iOS | ||
| Android | ||
| Self-hosted |
Mattermost facts
1 of 3 verified- Self-hosting
- Yes
- Checked Oct 24, 2026mattermost.com(opens source in a new tab)
- “collaboration, automation and AI in private cloud, self-hosted, and air-gapped environments.”
Slack facts
3 of 3 verified- Free plan
- Yes, with limited history
- Checked Oct 24, 2026slack.com(opens source in a new tab)
- “Or start with the basics for free, and upgrade at any time.”
- Platforms
- Web, desktop, mobile
- Checked Oct 24, 2026slack.com(opens source in a new tab)
- “Downloads | Slack Skip to main content Product COLLABORATE Channels”
- Owner
- Salesforce
- Checked Oct 24, 2026slack.com(opens source in a new tab)
- “AI Save time with built-in AI Agentforce Team up with Salesforce agents CONNECT Apps & Integrations Connect your favorite”
Pros and cons of Mattermost
- Open source and self-hosted
- Slack-like interface
- Strong compliance options
- Self-hosting requires maintenance
- Smaller integration catalog than Slack
Pros and cons of Slack
- Huge integration ecosystem
- Polished threads and huddles
- Shared channels with other companies
- Free plan hides older message history
- Costs rise quickly per seat
Other apps to consider
Google ChatInstead of Slack
Included with Google Workspace, so no extra subscription if you already use it.
Mattermost vs Slack: common questions
Is Mattermost better than Slack?
Slack suits companies that want hosted chat with the largest integration ecosystem and are comfortable with Salesforce holding their data. Mattermost suits security-conscious organisations, such as government, defence and finance teams, that need to self-host chat on their own infrastructure. The biggest difference is control: Mattermost is open source and runs where you choose, while Slack is a managed cloud service with less maintenance and more integrations.
Is Mattermost free?
Yes. Mattermost is free, open-source software you can host yourself.
Is Slack free?
Slack has a free plan, with paid plans for more features. See its verified pricing facts above for current limits.
Is Mattermost or Slack open source?
Mattermost is open source; Slack is not.
Which platforms do Mattermost and Slack support?
Mattermost: Web, Windows, macOS, Linux, iOS, Android and Self-hosted. Slack: Web, Windows, macOS, Linux, iOS and Android.