Mattermost
Open-source, self-hosted team chat built for classified and air-gapped government use.
On the record
Checkpoint: Mattermost Docs Joint Development Program moves from prototype to shipped product
The call
Mattermost traded a shrinking Slack-alternative market for a defense niche that Microsoft can't easily enter yet, but hasn't raised money in seven years while building it out.
Mattermost makes messaging software for governments and militaries that need to keep conversations secret and on their own computers, not in the cloud. It is hard to replace because government agencies face strict security rules that regular products like Slack and Microsoft Teams cannot meet, and switching costs are high once teams build custom workflows around it. The big risk is that Microsoft, which currently helps Mattermost run on government clouds, could build its own competing product for the same customers, and Mattermost's security record matters more than ever as hackers find more problems in the software each month.
Why
01
AI pressure: None apparent. Cloud AI labs can't touch classified, air-gapped systems, so Mattermost's core niche stays outside their reach for now. Could AI do the core job? Unlikely.
02
Bigger players: Microsoft Teams via Azure Government Secret/Top Secret. Microsoft is Mattermost's cloud partner today but is building the same sovereign-government stack it could sell direct tomorrow. Could a giant copy it? No, they are blocked.
03
What protects it. Government certifications (IL2 to IL6, PL3, NATO accreditation) that take years to earn and lock in defense buyers.
What would change this call
Whether Microsoft ships an allied-nation-certified sovereign collaboration stack on Azure Government by 2027. Would show Microsoft shifting from Mattermost's cloud partner to a direct predator in its defense niche.
Whether Mattermost announces a new priced funding round or discloses a large defense contract within a year. Would clarify if the 7-year funding gap reflects quiet profitability or capital constraints.
Whether Mattermost's annual CVE count for 2026 exceeds the 2025 total of 90. Would test whether security incidents are undermining the trust moat central to its defense positioning.
Whether Mattermost announces a new priced funding round or discloses a large defense contract within a year. Would clarify if the 7-year funding gap reflects quiet profitability or capital constraints.
Whether Mattermost's annual CVE count for 2026 exceeds the 2025 total of 90. Would test whether security incidents are undermining the trust moat central to its defense positioning.
Key numbers
- Revenue estimates range $13M to $34.7M
- No priced funding round since $50M Series B
- CVEs: 108 in 2026 YTD vs 90 in all of 2025
Named risks
- CVE disclosures rose to 108 in 2026 YTD vs 90 in all 2025, undermining security-first brand.
- No priced funding round since 2019 and undisclosed valuation despite new C-suite build-out.
- Microsoft could shift from Azure Government partner to direct sovereign-collaboration competitor.
- Wildly conflicting third-party revenue estimates ($13M to $34.7M) signal financial opacity.
Rivals, as read in July 2026
| Rival | Direction | Evidence |
|---|---|---|
| Microsoft Teams | contesting | Azure Government Secret/Top Secret partner since Jan 2025, positioned as potential sovereign-cloud predator |
| Slack | losing to | Slack holds ~94% Internal Communications share vs Mattermost ~0.11% per 6sense, n.d. |
| Rocket.Chat | contesting | Open-source self-hosted messaging rival in same defense-adjacent niche |
| Microsoft Teams and Slack (overall commercial market) | losing to | Mindshare fell 3.4% to 1.8% YoY per PeerSpot, 2026-05-04 |
Questions people ask
- Is Mattermost profitable in 2026?
- No profitability figures are disclosed. Third-party revenue estimates range from $13M (RocketReach) to $34.7M (Datanyze), and Mattermost has not raised a priced funding round or disclosed a valuation since its $50M Series B in 2019, as of 2026-07-14.
- Who owns Mattermost?
- Mattermost is a privately held, venture-backed company co-founded by CEO Ian Tien and CTO Corey Hulen. It has not been acquired or gone public, and no valuation has ever been publicly disclosed as of 2026-07-14.
- Could AI replace Mattermost?
- Unlikely in its core defense niche: Mattermost's air-gapped, classified deployments (IL2-IL6, PL3, NATO-aligned) cannot be served by cloud AI tools that lack clearance to touch classified data. But generic team-chat AI features in Slack and Teams pressure its commercial-market use case.
- Is Mattermost losing market share to Slack and Microsoft Teams?
- Yes. PeerSpot's Enterprise Social Software tracker shows Mattermost's mindshare falling from 3.4% to 1.8% year over year as of 2026-05-04, while 6sense reports Slack holds roughly 94% of the Internal Communications category versus Mattermost's 0.11%.
- Who is Mattermost's biggest competitor?
- Microsoft Teams is the named threat: it's currently a partner via Azure Government Secret/Top Secret cloud but is positioned to compete directly in allied-sovereign defense collaboration. Rocket.Chat also contests the same open-source, self-hosted niche.
- Has Mattermost raised any new funding recently?
- No. Its last priced round was a $50M Series B led by Y Combinator Continuity in 2019. As of 2026-07-14, seven years have passed without a new priced funding round, and no valuation has been disclosed.
Timeline
- 2026-06-02Launched Mattermost Agents v2.0 with Model Context Protocol tool support
- 2026-05-15Released Mattermost v11.7 with granular ABAC and custom AI prompts
- 2026-04-30Appointed first Chief People Officer, Lane McFarland, to scale workforce
- 2026-04-22Appointed Adam Enterkin (ex-BlackBerry) as Chief Revenue Officer
- 2026-03-24Launched Joint Development Program for sovereign Confluence successor, Mattermost Docs
- 2026-03-23Opened Japan subsidiary, expanded Pacific defense operations for Microsoft
- 2025-10-16Launched free 'Mattermost Entry' tier for government evaluation
- 2025-06-17Launched Enterprise Advanced tier for multi-domain defense operations
- 2025-05-27Announced AI-powered collaboration for Azure Secret and Top Secret clouds
- 2023-02Laid off about 30 employees, roughly 15% of staff
Revision history
22 July 2026
First assessed. Protection under test. The text above is fixed as of this date and is not edited afterwards.
In the same band
Sources
- How Much Did Mattermost Raise? Funding & Key Investors (2025-02-26)
- Mattermost Revenue, Funding & Growth History (2024) (2024-12-18)
- Mattermost (2026-03-16)
- Products, Competitors, Financials, Employees (2025-09-16)
- $50M Series B in Mattermost as open source Slack alternative
- Valuation, Funding, Investors (2026-07-14)
- Management and Employees List
- Contact Details and Business Profile
- Companies that use Mattermost (697)
- Mattermost vs Microsoft Teams (2026) (2026-05-04)
- Company Profile
- Tech layoffs tracker 2026 (2026-07-20)