Mattermost

What is Mattermost?

Mattermost is an open source, self-hosted team chat platform that keeps your organization’s messaging on your own servers. It gives you channels, direct messages, threaded discussions, file sharing, voice calls, and integrations — the day-to-day of a tool like Slack — without sending any of that data to a vendor’s cloud.

What is Mattermost best for?

Organizations that need chat but can’t hand their conversations to a SaaS provider — government, defense, healthcare, finance, and other regulated or security-conscious teams. It’s also a natural fit for DevOps teams that want incident response and tooling wired into the same place they talk. If you want a hosted experience with zero servers to manage, it’s a worse fit than Slack — and it sits alongside other open source team chat options like Rocket.Chat.

What can Mattermost do?

• Organize conversations into channels, group and direct messages, and threaded replies, with file sharing and full-text search
• Run as a single Go binary on Linux, backed by PostgreSQL, with Docker, Kubernetes, and Helm deployment options
• Use native apps for web, Windows, macOS, Linux, iOS, and Android
• Make 1:1 and group voice calls with screen sharing (live transcription and AI meeting summaries on paid tiers)
• Coordinate incident response and repeatable processes with collaborative Playbooks
• Connect your stack through webhooks, slash commands, a plugin framework, a REST API, and bots for GitHub, GitLab, Jira, and more

Where does Mattermost fall short?

• The free editions are confusing. Team Edition (the MIT-licensed build) has no message limit but, as of 2025, no SSO at all; the unlicensed Enterprise build instead runs as “Entry Edition,” which hides everything past 10,000 messages server-wide from search and view.
• Core access controls are paywalled. SSO/SAML, enforced multi-factor auth, guest accounts, and compliance features (audit logs, data retention) require the paid Professional or Enterprise plans — the free Team build authenticates with email and password only.
• Its integration catalog is thinner than Slack’s. There are fewer ready-made app integrations, so you’ll wire more of your own tooling through webhooks, plugins, and the API.

Is Mattermost free?

Yes — Team Edition is free, open source, and self-hosted with no per-user fee and no message cap; you only pay for the server it runs on. Paid tiers add access and compliance controls: Professional is a per-seat subscription (historically around $10/user/month) and Enterprise is custom-quoted. The catch is that the free Team build has no SSO, and the free unlicensed Enterprise “Entry” build caps viewable history at 10,000 messages.

What does Mattermost replace?

Mattermost is a self-hosted alternative to Slack and Microsoft Teams. It covers the same channel-based messaging, calls, and integrations, but runs on your own infrastructure so your conversations and files never leave systems you control.

FAQ

Is Mattermost open source? Yes. The compiled Team Edition is released under the MIT license (the underlying server source is AGPLv3 or a commercial license), while the enterprise directory is source-available. The core chat platform is genuinely open source.

Can I self-host Mattermost for free? Yes. Team Edition is free with no per-user fee and no message cap. You need a Linux server and a PostgreSQL database — Mattermost ships as a single Go binary.

Is Mattermost a good Slack alternative? For teams that must keep data on their own infrastructure — regulated industries, government, security-conscious orgs — yes. Expect fewer off-the-shelf integrations than Slack, and note that SSO is a paid feature.

What do I need to run Mattermost? A Linux server and a PostgreSQL database. Deploy the single Go binary directly, or use the official Docker, Kubernetes, or Helm options.