Mattermost

Open Source

Accelerate your mission critical workflow by integrating people, processes, tools and AI…

Unlimited Free TierOpen Sourcefrom $10/user/mo

Free plan checked against Mattermost's pricing page on 2 September 2026. Re-checked monthly.

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About Mattermost

Mattermost is a self-hosted Slack alternative aimed at engineering, security and defence teams that cannot put chat in a SaaS vendor's cloud. It runs on your own servers or in air-gapped networks. The current free option is Mattermost Entry, a limited-use edition of Enterprise Advanced that every install starts with.

What the free plan gives you

Entry includes the full Enterprise Advanced feature set: channels, threads, file sharing, 1:1 and group calls with screen sharing, Playbooks, Boards, AI Agents, and integrations. Mattermost's docs say it is suited to teams under 50 users, with community support only. Because it is self-hosted there is no per-user charge; you supply the server. The older open source Team Edition is still available on GitHub for those who want the source-based build.

Where the free plan stops

The headline limit is message history: Entry shows and searches only the most recent 10,000 channel messages across all channels. Older messages stay in the database but are not viewable until you license. Hard usage rate limits apply as well. The paid Professional tier lifts those limits, supports up to 250 users and adds business-hours support; third-party listings put it at $10 per user per month billed annually with an 11-user minimum, though Mattermost's pricing page itself does not print the figure. Enterprise and Enterprise Advanced are quote-based.

Who it suits

A team of five to twenty that wants sovereign chat and can host it will do well on Entry, particularly if history beyond 10,000 messages is not critical. Larger teams or anyone who needs full searchable archives should plan for Professional from the start.

Key Features

Adaptable

Focused

Secure

Resilient

Self Sovereign Collaboration

Integrated Security Operations

Command + Control

Real-Time DevSecOps Collaboration

Pros & Cons

Open source — self-host it for nothing

Free tier has no hard usage ceiling

Covers adaptable on the free plan

Free plan verified against the vendor's pricing page

Vendor does not publish a clear free-plan breakdown

The free plan in practice

What you can actually do on Mattermost's free plan (Free self-hosted Entry edition, 10k message history), where it stops, and when it's worth paying.

What you can do free

Full Enterprise Advanced feature set for evaluation
Channels, threads, calls and screen sharing
Playbooks, Boards and AI Agents
Self-hosted, no per-user fee
Suited to teams under 50 users

Where it stops

Only the latest 10,000 channel messages visible and searchable
Community support only
Hard usage rate limits

When to upgrade to a paid plan

Mattermost is open source, so self-hosting is free and unlimited. The only reason to pay is convenience: choose a hosted or cloud option when you'd rather not run and maintain it yourself, or need official support.