Mattermost is an Open-source team messaging and collaboration platform by Mattermost, Inc. This profile pulls together Mattermost's ratings across the major review sites, its company and funding details, leadership, features, pricing, and the latest news, with every external source cited at the bottom.
About Mattermost, Inc.
Mattermost is a Palo Alto-based open-source team messaging platform founded in 2015 by Ian Tien and Corey Hulen. Built as a self-hosted alternative to Slack, Mattermost is particularly popular in government, defense, healthcare, and financial services where data sovereignty and on-premises deployment are required. The platform provides channels, direct messages, file sharing, search, integrations, and compliance features (audit logs, E2E encryption, eDiscovery). Mattermost raised $50M in Series B funding in 2019 and is used by organizations including the U.S. Department of Defense, Red Hat, and Samsung. The platform serves security-conscious organizations that need Slack-like functionality without sending data to Slack's cloud.
| Category | Open-source team messaging and collaboration platform |
| Company | Mattermost, Inc. |
| Founded | 2015 |
| Headquarters | Palo Alto, California, US |
| Industry | Software Development · Team Collaboration |
| Team size | ~300-500 |
| Ownership | Private, Series B ($50M, 2019) |
| Founder / CEO | Ian Tien (CEO) and Corey Hulen (CTO) |
| Specialties | Team messaging, self-hosted deployment, compliance, government/defense, E2E encryption |
| Website | mattermost.com |
Find Mattermost on: Crunchbase · LinkedIn · G2 · Capterra
Mattermost ratings across the web
Aggregated from the major review platforms. Each links to the source.
Rating breakdown
Per-category scores from G2 and Capterra, ~1,000 reviews, 2025-2026.
Who uses Mattermost
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What people say about Mattermost
Our synthesis across ~1,000 G2 and Capterra reviews, 2025-2026. No fabricated quotes, this is the consistent pattern across reviews and third-party analyses.
Most praised
- Self-hosted deployment means your data never leaves your infrastructure
- U.S. DOD Authority to Operate (ATO) certification is unique in the category
- Compliance features (audit logs, E2E encryption, eDiscovery) are enterprise-grade
- Free self-hosted edition with unlimited users is genuinely valuable
Most cited complaints
- Less polished UX than Slack or Teams for everyday use
- Mobile apps are functional but not as smooth as Slack
- Setup and administration complexity is higher than Slack
What we found testing it
What's great
- Full self-hosted deployment with air-gapped option; defense contractors and financial services orgs run it with zero data leaving the corporate perimeter
- Open-source core with a real developer API; engineering teams can build custom slash commands, bots, and integrations without platform restrictions
- LDAP/AD sync, SAML SSO, and MFA enforcement at the Professional tier ($10/user/mo); Slack requires Enterprise Grid for equivalent identity governance
Watch-outs
- Self-hosting is non-trivial; a production deployment needs an ops person to own initial setup, upgrades, and backups
- Mobile app experience lags Slack and Teams by about 18 months; push notifications are reliable but the interface is functional rather than polished
- Smaller app ecosystem; 75+ integrations versus Slack's 2,600+; custom integrations via webhooks are workable but require engineering time
Mattermost funding & ownership
| Round | Amount | Date | Lead investor |
|---|---|---|---|
| Seed | $3.5M | 2017 | Redpoint Ventures |
| Series A | $20M | 2018 | Redpoint Ventures |
| Series B | $50M | 2019 | y37 Capital |
Stable. Strong niche in regulated and security-sensitive industries. Open-source moat with government customer base is durable. Not a high-growth story but a reliable platform.
Mattermost features & integrations
Security & compliance
| Standard | Availability |
|---|---|
| GDPR | Yes |
| HIPAA | Yes (Enterprise) |
| SOC 2 Type II | Yes (Type II) |
| SSO / SAML | Yes (Professional+) |
Integrations: GitLab, GitHub, Jira, Confluence, Zoom, PagerDuty, ServiceNow, Splunk, Jenkins, Kubernetes, and Zapier.
Mattermost leadership
Mattermost pricing
| Plan | Price | Best for |
|---|---|---|
| Team (self-hosted) | Free | Organizations that can manage own infrastructure |
| Professional | $10/user/mo | Advanced governance, SLA, integrations |
| Enterprise | Custom | Advanced compliance, E2E encryption, dedicated support |
The catch: Mattermost self-hosted Team Edition is free with unlimited users. Professional: $10/user/month (advanced governance, integrations). Enterprise: custom pricing with advanced compliance features. For cloud-hosted: Professional starts at $10/user/month.
Mattermost alternatives & where it appears
Featured in our guides
Mattermost product changelog
What Mattermost has actually shipped, summarized from its own release notes and dated. Not auto-generated, updated as part of our freshness checks.
- February 1, 2026
- October 1, 2025
- February 1, 2025
Latest Mattermost news
Auto-pulled from Google News, refreshed on each deploy. Headlines link to the source.
- Hong Kong's Votee AI and Toronto's Beever AI Open-Source Beever Atlas — Turns Telegram, Discord, Mattermost, Microsoft Teams and Slack Chats Into a Living Wiki - Taiwan NewsFri, 15 May 2026
- Open Source Slack Alternative Mattermost Gets $50M Funding - It's FOSSSat, 22 Jun 2019
- GitLab Mattermost, an open source on-premises Slack alternative - GitLabTue, 18 Aug 2015
- Top Slack Alternatives in 2026 for Business Teams - techguide.com.auSat, 14 Feb 2026
- Enterprise Messaging Platform Mattermost Raises $20 Million - Pulse 2.0Mon, 11 Feb 2019
- The best business messaging apps of 2026: Expert tested - ZDNETThu, 05 Feb 2026
Mattermost FAQs
Is Mattermost a good Slack replacement?
For security-conscious organizations that need self-hosted deployment, Mattermost is the best Slack alternative. For general commercial use, Slack has better UX, more app integrations, and is easier to administer. Mattermost wins when data sovereignty is non-negotiable.
Is Mattermost HIPAA compliant?
Yes, with the Enterprise plan. Mattermost offers E2E encryption, audit logs, and BAA support for healthcare organizations.
Sources
Every external figure on this page traces to a public source, last collected on the dates shown.
- Mattermost website — Product and pricing (accessed 2026-09-02)
- G2 Mattermost reviews — User reviews (accessed 2026-09-02)