Companies Using Mattermost

With 10+ years analysing web technology footprints, I've spent the last few weeks pulling Mattermost's shape out of our crawl data, and it's one of the most geographically distinct profiles I've seen in the collaboration category. As of our April 2026 crawl, TechnologyChecker.io tracks 1,590 domains running Mattermost, with 1,391 matched to enriched LinkedIn company profiles (a 68.25% match rate, unusually high because so many detections are universities and research bodies with clear LinkedIn presences). This analysis pulls together detection history, migration flows, size and age breakdowns, and customer stories from Mattermost's own case study library.

Growth trajectory

Our first Mattermost detection was January 2020 on a single domain. By September 2020 that had jumped to 476 active domains, the spike timed with the COVID-era push to self-hosted collaboration described in the DoD's own case study, which describes Platform One rolling Mattermost out to 48,000 DoD employees in a single week. Unlike the consumer messaging tools that popped and flattened, Mattermost kept climbing: 710 by end of 2021, 952 by end of 2022, 1,221 by end of 2023, and a peak of 1,623 in December 2024. That's roughly 3.4x growth across three years, a steady rate for a self-hosted product where each deployment means real infrastructure work. The open-source server repo has picked up 36,300+ stars and 8,500+ forks on GitHub since it was first published in June 2015. The sharp 2025 drop in the chart is a detection artifact from a change in our crawl coverage, not churn. The Market Share API still shows 1,590 active domains in the most recent category snapshot.

"Mattermost's growth curve doesn't look like a SaaS growth chart. It looks like an open-source adoption chart: slower onboarding, stickier retention, and pronounced upticks around regulatory events like GDPR enforcement and the Schrems II ruling." - Mehmet Suleyman, CEO at TechnologyChecker.io

Sales Signal: This is a maturing but still-expanding market. Per public Latka data, Mattermost hit $33.1M revenue with a 156-person team in 2024, a modest footprint that still produces disproportionate deployment density. The addressable pool is not infinite, self-hosting appeals to a specific buyer archetype, but the customer base has roughly doubled in three years and new deployments are still outpacing churn in our data.

Customer profile

Two numbers explain most of Mattermost's profile. First, 54.4% of customers have 1-10 employees, and another 19.8% have 11-50. That's roughly three-quarters of the base sitting in the small-to-very-small range, which is consistent with open-source adoption, individual dev teams or research groups self-host before procurement teams get involved. Second, 40.45% of customers were founded in the 2010s, and another 21.66% in the 2000s. Two-thirds of the base is digital-native or digital-transformed rather than purely legacy.

But the enterprise tail is where things get interesting. Our data shows 28 customers with 10,000+ employees, including Tesla (teamchat.tesla.com), Mercedes-Benz (matter.i.mercedes-benz.com), Textron, O'Reilly Auto Parts, and iQor. These are subdomain deployments, not company-wide messaging infrastructure, the primary vendor is almost certainly Slack or Microsoft Teams at that scale. But a DevOps team, a security operations group, or an air-gapped engineering project picked Mattermost for that specific workload. That pattern matches what Mattermost's own case studies describe: Air Mobility Command runs ChatOps workflows on Mattermost, while CERN integrates ~100 tools into it for global scientific collaboration, and Rocky Linux runs 5,300+ active community members on a single high-availability cluster.

Sales Signal: Mattermost sells into two distinct motions. At the 1-50 employee tier, the buyer is a technical lead picking a self-hosted tool for data or cost reasons. At the 10,000+ tier, the buyer is a specific team (DevOps, security, research) with a compliance or data-sovereignty constraint their primary tool can't meet. Different pitches, different champions, different procurement paths.

Industry and geographic concentration

Mattermost is the first technology I've profiled in this category where Germany (271) outranks the United States (202). France is third at 101, and the Netherlands, UK, Italy, Austria, Switzerland, and Spain add another ~250 combined. European countries together account for roughly 60%+ of the tracked base. Russia also shows up at 33, unusual for a U.S.-headquartered SaaS peer, and a sign that self-hosting removes most of the geopolitical friction around SaaS procurement.

On industry, IT Services (17.67%) and Software Development (15.49%) together exceed 33%. Add in Technology/Internet (6.38%), IT & Services (3.97%), and Computer/Network Security (1.87%), and more than 45% of the base is in some form of technology services. The next meaningful clusters are Higher Education (3.74%) and Research Services (3.27%), the European university signal. Financial Services (1.63%) and Telecommunications (1.63%) round out the long tail. Mattermost has leaned into this positioning publicly: the company now describes itself as "the leading sovereign collaboration and AI automation platform for national security and critical infrastructure enterprises".

Sales Signal: Germany and France are underpriced prospects relative to the U.S. for Mattermost-adjacent tooling. German-speaking DACH (Germany, Austria, Switzerland) contains 324 tracked customers by itself, a single regional territory the size of a U.S. national segment for many competitors.

Migration patterns

This is where the data gets sharpest. Looking at companies that switched between Mattermost and its competitive set:

Mattermost beats Rocket.Chat 5.7:1. 120 companies switched from Rocket.Chat to Mattermost, while only 21 went the other way. That's the clearest head-to-head win in the dataset. If you're pitching against Rocket.Chat in a self-hosted deal, you're pitching from a position of strength.

Mattermost loses to Slack 36:1. 585 companies have switched from Mattermost to Slack in the observable window, while only 16 have come back. That's not a competitive battle, that's a lifecycle. Teams pick Mattermost when self-hosting is a hard constraint (pre-funding, air-gapped, regulated), then migrate to Slack once that constraint lifts. The 1-year window (36 gone to Slack in the last year) is noticeably slower than the 3-year window (585), so the bleed has softened recently.

Against Discourse, it's a wash. 37 in each direction. Discourse and Mattermost solve overlapping but different problems, Discourse for long-form community threads, Mattermost for real-time team chat. Movement between them usually reflects a use-case rethink, not a loss.

"The 585-to-16 Slack migration corridor is the single biggest retention risk in Mattermost's customer base, but it's also a revenue opportunity for anyone building migration tooling, managed hosting, or compliance-first add-ons that make self-hosting less painful." - Mehmet Suleyman, CEO at TechnologyChecker.io

Sales Signal: Two two-sided opportunities. First, Slack migration services, 585 companies is a credible segment for tools that make moving from Mattermost to Slack cleaner. Second, Mattermost retention tooling, any product that reduces the operational cost of self-hosting (managed Mattermost, compliance automation, DR tooling) has a live, addressable list in our export.

Technology ecosystem

Mattermost customers run an unusually European infrastructure stack. Hetzner (25.18%) is the single most common hosting provider, that's a German company, and its dominance here is a strong proxy for Mattermost's overall geographic centre of gravity. Cloudflare Hosting is close behind at 24.89%, and OVH adds another 11.87%. Put together, European hosts account for more than 40% of tracked infrastructure.

On CMS co-occurrence, Atlassian Cloud (7.27%) and Drupal (7.27%) tie for first. Atlassian Cloud presence signals Jira and Confluence integration patterns, this is a DevOps-heavy customer base that's also using project management tools. TYPO3 at 4.46% is a strong European signal (TYPO3 is the dominant government and enterprise CMS in German-speaking markets).

On the analytics side, it's standard: Google Analytics (52.88%), Global Site Tag (47.84%), Cloudflare Radar (34.68%). Nothing unusual there. The JavaScript framework profile shows some aging, AngularJS (22.16%) and Vue v2 (21.87%) outpace newer versions, consistent with a customer base that's established rather than chasing the latest release.

Sales Signal: If you sell DevOps, observability, or compliance tooling, the high Atlassian Cloud overlap is a tell, Mattermost customers have already accepted the integration tax of running multiple best-of-breed tools. Low overlap categories (security operations tooling, SIEM, vulnerability management) are the upsell gaps.

G2 review signals

G2's AI summary of Mattermost reviews puts ease of use (15 mentions), reliability (14), and smooth integrations (11) as the top positives. Security controls (10) also lands in the top five, reviewers are calling out the same data-ownership benefit our migration data shows teams choosing Mattermost for.

The top complaint, unintuitive interface (8 mentions), lines up neatly with our migration loss to Slack. Teams that have a choice about where to chat tend to choose the product with the lower UX friction, and Slack has a two-decade head start on polish. Performance issues on mobile and search (8 mentions) is the second most common con, and this one cross-references with our migration data too: long-tail enterprise deployments (the 28 companies at 10,000+ employees) are exactly where mobile and search break first.

Sales Signal: The G2 data says Mattermost has a UX problem, not a feature problem. If you build channel navigation, search, or mobile experiences, Mattermost's enterprise tier is a receptive market. If you sell a rival, lead with the UX argument and not the feature argument, the feature parity is closer than teams realise.

Key takeaways

1. Mattermost is in a mature-growth phase. 3.4x domain growth in three years, with the 1-year rate still positive but softening. The product is backed by roughly $70M in funding, including a $50M Series B led by Y Combinator Continuity in June 2019 at a $322.96M valuation per ForgeGlobal.

2. The core customer is a 1-50 employee European tech team with data sovereignty as a top-three requirement. The secondary customer is a 10,000+ regulated enterprise using Mattermost for a specific workload, not company-wide chat.

3. Mattermost wins head-to-head against other open-source self-hosted messaging (Rocket.Chat, 5.7:1). It loses to Slack when teams outgrow the self-hosting constraint.

4. Geography is the single most distinctive feature. Germany > U.S., DACH > any single country, Europe >= 60% of the base.

5. The infrastructure stack (Hetzner, OVH, TYPO3, Drupal, Atlassian) paints a picture of compliance-first, integration-heavy, Europe-centric buyers. The June 2025 launch of Mattermost Enterprise Advanced targets exactly that buyer: defence, intelligence, and critical infrastructure running multi-domain operations.

Sales applications

Outreach template (to IT leadership at mid-sized European firms): "Your team shows up in our data as a Mattermost customer, and our detection shows you're running it on {host}. Based on the 1,391 Mattermost customers we've analysed, about 40% of peers your size use {adjacent_tool}. Worth a 15-minute call to compare notes?"

Targeting strategy: Filter on TechnologyChecker.io for technology=Mattermost, country IN (Germany, France, Netherlands, Switzerland), employees IN (51-200, 201-500). That's roughly 120-150 high-fit, ICP-matched accounts.

Competitive angle: If you sell hosted/SaaS collaboration, the Mattermost migration list to Slack (585 companies) is your warm lead pool. These are companies that have already self-selected away from the self-hosted approach. If you sell compliance or managed self-hosting, the inverse list (the 1,391 active Mattermost customers) is your addressable market.

Explore the full list of companies using Mattermost on TechnologyChecker.io, all 1,391 enriched customers, filterable by size, industry, country, and technology stack. Our dataset covers 29.6M crawled domains and 44,000+ tracked technologies.