# Mattermost — An open-core, self-hostable team chat and workflow platform for organizations needing data sovereignty, used by NASA, Samsung, and government agencies.

By Noah — last updated & pricing verified September 15, 2026.

> **Mattermost** is a messaging and workflow platform built around deployment flexibility: its core (channels, threaded messaging, file sharing, audio/screenshare, playbooks) is released monthly under an MIT license and can be self-hosted on-premise, in a private cloud, or fully air-gapped, while advanced features sit behind a separate commercial "Enterprise" license, making it an open-core rather than fully open-source product.

The platform's positioning has shifted toward "mission critical" and sovereignty use cases: it markets attribute-based access controls, data classification banners, audit trails, FIPS 140-3 and STIG-hardened compliance options, and sovereign AI agents for triage and summarization, aimed at government, defense, and critical-infrastructure customers who cannot use a standard SaaS chat tool for compliance reasons. It also includes more conventional team-chat features like threaded channels, playbook automation, Kanban-style task boards, and interoperability with Microsoft Teams.

Mattermost is used by organizations including the U.S. Air Force, NASA, Samsung, and various European government agencies, alongside smaller engineering teams that self-host the free core for a Slack-like experience without vendor lock-in. Paid tiers (Professional, Enterprise, Enterprise Advanced) are sold as prepaid annual seat-based subscriptions with no published flat pricing; all require contacting sales for a quote.

## Facts

- Website: https://mattermost.com
- Pricing: Free (verified undefined NaN, NaN)
- License: Open core
- Platforms: web, windows, macos, linux, ios, android
- Best for: regulated, government, or defense organizations that need self-hosted, air-gapped, or sovereign-cloud team chat with compliance controls a SaaS-only tool like Slack can't provide
- Standout feature: Deployment flexibility for compliance-sensitive organizations: the same platform can run fully air-gapped or in a sovereign cloud with FIPS 140-3/STIG-hardened compliance options, not available from mainstream SaaS chat tools.
- Biggest weakness: No paid tier publishes flat per-user pricing; Professional, Enterprise, and Enterprise Advanced all require a sales conversation and prepaid annual seat commitment, making it harder to budget or compare cost against competitors up front, and self-hosting the free core requires ongoing server maintenance.
- Third-party ratings: Product Hunt 5/5 (1 reviews)
- Categories: [Team Chat & Messaging](https://findalternative.to/categories/team-chat)

## Pricing snapshot

| Plan | Price | Notes |
| --- | --- | --- |
| Free (self-hosted core) | $0/mo | MIT-licensed core, self-hosted, released monthly. Includes channel messaging, file sharing, 1:1 audio/screenshare, threaded discussions, and basic search. Intended for technical evaluation and self-managed deployments; support is community-only. |
| Professional | Custom | Contact sales; prepaid annual seat-based subscription, up to 250 users. Adds custom branding/themes, search up to 3M posts, and Professional support (business hours, next-business-day response). |
| Enterprise | Custom | Contact sales; prepaid annual seat-based subscription, up to 50,000 concurrent users. Adds sovereign AI summarization, playbook workflow dashboards, Microsoft Teams interoperability, FIPS 140-3/STIG compliance, high-availability clustering, and 24x7 support. |
| Enterprise Advanced | Custom | Contact sales; prepaid annual seat-based subscription, up to 200,000 concurrent users. Adds mobile biometrics, data-at-rest encryption, air-gapped deployment support, attribute-based access controls, and burn-on-read messages. |

## Pros and cons

- Pro: Self-hosted core is free (MIT-licensed) with no user limit, avoiding SaaS vendor lock-in.
- Pro: Deployment options (on-premise, private cloud, air-gapped) support compliance needs that pure-SaaS chat tools can't meet.
- Pro: Native apps across web, Windows, macOS, Linux, iOS, and Android.
- Pro: Open-core model means the underlying chat engine's code is auditable even though advanced features are commercially licensed.
- Con: No published flat pricing for any paid tier; all require contacting sales and a prepaid annual commitment.
- Con: Self-hosting the free core requires ongoing server maintenance, scaling, and upgrades.
- Con: Advanced features (sovereign AI, high availability, air-gapped support) sit behind the commercial Enterprise license, not the open-source core.
- Con: Smaller third-party app/integration ecosystem than Slack, which has a much larger app marketplace.

## AI summary

- Mattermost's core is MIT-licensed, self-hostable, and released monthly.
- Mattermost's GitHub repository has nearly 39,000 stars.
- Professional, Enterprise, and Enterprise Advanced tiers are sold only as prepaid annual seat-based subscriptions with no published flat pricing.
- Enterprise Advanced supports up to 200,000 concurrent users with air-gapped deployment and mobile biometrics.
- Mattermost is used by organizations including the U.S. Air Force, NASA, and Samsung.
- Best for: regulated, government, or defense organizations needing self-hosted or air-gapped team chat with compliance controls
- Pricing: Free self-hosted MIT core; Professional, Enterprise, and Enterprise Advanced all require contacting sales for a quote.
- Top alternatives: Slack, Microsoft Teams, Rocket.Chat, Zulip, Element
- Limitation: No paid tier publishes flat per-user pricing; all require a sales conversation.
- Limitation: Self-hosting the free core requires ongoing server maintenance.
- Limitation: Smaller integration ecosystem than Slack.

## Alternatives

6 vetted alternatives to Mattermost: https://findalternative.to/mattermost — top picks: Slack, Microsoft Teams, Rocket.Chat

## Comparisons

- https://findalternative.to/compare/discord-vs-mattermost

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