Open-source, self-hosted team messaging platform designed for organisations that need full data sovereignty. Features end-to-end encryption, granular permissions, multi-factor authentication, SAML/LDAP SSO, compliance exports, and an AI Copilot plugin that connects to any LLM (local or cloud). Available as self-hosted or secure cloud deployment with DevOps-oriented integrations.
Our take
Mattermost exists for one reason: organisations that cannot put their communication on someone else's servers. Government agencies, defence contractors, healthcare systems, and security-conscious companies where Slack's cloud model is a non-starter. The free self-hosted tier is genuinely unlimited — no message history caps, no user limits, no integration restrictions. That alone makes it the most generous free offering in the category. The AI Copilot plugin is notably flexible: connect it to your own local LLM (Llama, Mistral) or any cloud provider, keeping AI processing within your infrastructure. Thread summarization and action-item extraction work across any connected model. The trade-off is everything you'd expect from self-hosted software: you own the deployment, upgrades, backups, and uptime. The UX is functional but uninspired compared to Slack's polish — it looks and feels like an open-source project, because it is. The integration ecosystem skews heavily DevOps (GitHub, GitLab, Jenkins, PagerDuty) with limited support for marketing, sales, and general business tools. Professional at $10/user/mo annual is fair for SSO and advanced permissions, but you're still hosting the infrastructure yourself (or paying for their secure cloud, priced separately).
Product roadmap
Mattermost is positioning as the 'secure AI collaboration' platform — the Agents plugin allowing teams to run any LLM within their own infrastructure is the differentiator they're doubling down on. The roadmap focuses on multilingual AI support, GitHub integration enhancements, and deeper workflow automation via Playbooks. The company isn't trying to compete with Slack on UX polish; it's competing on data sovereignty and self-hosted AI — a niche that grows more valuable as AI regulation tightens.
Who is Mattermost for?
Self-hosting a messaging platform for one person is absurd overhead. Even the cloud option requires more administration than signing up for Slack or Discord.
Small teams with a DevOps engineer can run Mattermost effectively, but the administration burden is real. Only justified if your team handles sensitive data (healthcare, fintech, legal) where data sovereignty is a regulatory requirement, not a preference.
This is Mattermost's sweet spot. 50-200 person organisations with IT staff to manage the deployment, compliance requirements that rule out cloud messaging, and DevOps-heavy workflows that benefit from native GitHub/GitLab/Jenkins integrations.
Enterprise tier with high availability, compliance exports, custom admin roles, and 24/7 support is built for large organisations in regulated industries. Government agencies, defence contractors, and financial institutions are Mattermost's core enterprise market. The self-hosted model means no vendor has access to your communications — period.
Pricing
Free (Self-Hosted)
Free- • Unlimited users
- • Unlimited message history
- • Channels + DMs
- • File sharing
- • Basic integrations
- • Community support
Professional
$null/mo- • SAML/LDAP SSO
- • Read-only announcement channels
- • MFA enforcement
- • Guest accounts
- • Advanced permissions
Enterprise
$null/mo- • Compliance exports
- • Custom admin roles
- • High availability
- • Advanced compliance
- • 24/7 support (4hr SLA)
- • EMM/AppConfig
Pricing verified 2026-04-16
Ratings
Overall score: 74/100 (composite of the above ratings)
Features
core
ai
collaboration
integrations
Compare Mattermost with
Founded: 2015
HQ: Palo Alto, CA
Company size: 200-500
Last updated: 2026-04-16