Mattermost
Mattermost is a self-hosted open-source messaging and collaboration platform for technical and operational teams. Founded in 2016, it offers team messaging, file sharing, workflow automation, audio/screen sharing, and AI integration. Mattermost serves enterprise customers including the U.S. Department of Defense, NASA, and Samsung, with over 800,000 workspaces worldwide and 4,000+ community contributors.
Score generated by AI agents based on publicly cited evidence and reviewed by the project maintainer. Not independently validated.
Score History
Timeline events are AI-curated from public reporting. Score trajectory is derived from documented events.
SpinPunch open-sources its internal chat tool as Mattermost v1.0, released under MIT license at the request of the GitLab community. The platform is a pure open-source Slack alternative with no commercial tiers, no usage restrictions, and a growing contributor community. Enshittification risk is minimal: there is no venture capital, no paid features, and no distinction between free and enterprise users.
Mattermost secures $3.5M in seed funding and formalizes the open-core business model with Enterprise Edition E10, separating free and paid features for the first time. LDAP, multi-team support, and advanced access controls are gated behind the commercial tier at $3.25/user/month. The company remains small and community-oriented, but the structural incentive to move features behind the paywall is now in place.
Mattermost raises $70M in four months (Series A in February, Series B in June 2019) from Redpoint, Battery Ventures, and YC Continuity. The rapid capital injection creates growth pressure typical of venture-backed open-core companies. Feature gating intensifies, with MFA and guest accounts reserved for enterprise tiers. Community members on Hacker News begin questioning whether Mattermost qualifies as genuinely open source.
COVID-19 drives explosive growth as the USAF deploys Mattermost to 80,000 personnel on Platform One in 48 hours. Mattermost Cloud launches as a SaaS offering, v6.0 ships with Boards and Playbooks enabled by default, and the company unveils Government Solutions for defense and public sector. The platform expands from messaging into project management and incident response, but the product ambition stretches a team that has not yet found sustainable commercial footing outside government.
Two rounds of layoffs in 2023 cut the workforce by nearly 50%, from approximately 200 to around 156 employees. Mattermost abandons Boards to community maintenance, narrows its scope to messaging and workflow automation, and doubles down on the defense market. Revenue grows 59% from $20.7M to $33.1M by late 2024. Glassdoor reviews (3.3/5 stars) cite management transparency issues. The Copilot AI launch in June 2024 signals the next monetization vector, while MySQL support deprecation in v10 begins forcing infrastructure migrations.
The v11 release in October 2025 marked a sharp inflection point. Entry Edition imposed a retroactive 10,000-message limit on self-hosted instances, hiding data users had stored in their own databases. Team Edition lost GitLab SSO and Playbooks. Community backlash was fierce, with critics calling it a bait-and-switch and open-source betrayal. The 59% revenue growth from $20.7M to $33.1M between 2023 and 2024 suggested the monetization pressure was working commercially, even as it eroded trust.
Alternatives
The dominant team messaging platform with the deepest integration ecosystem. Not open source or self-hosted, but unmatched in app integrations and UX polish. Easy switch for teams not requiring self-hosting. Free tier has 90-day message history limit. Starts at $8.75/user/month.
Open-source team messaging platform with self-hosting, end-to-end encryption, and federation support. Similar feature set to Mattermost with no message limits on the free tier. Moderate switch — requires setting up a new server and migrating users, but no data lock-in if you control your database.
Open-source team chat with a unique topic-based threading model that helps organize conversations. Self-hostable with no message limits. Free cloud tier for small teams. Moderate switch — topic-based model is different from channel-based messaging and requires team buy-in.
Dimensional Breakdown
Summaries below were written by AI agents based on the cited evidence. They are editorial interpretations, not independent research findings.
Dimension History
Timeline (34 events)
SpinPunch Launches in Y Combinator Summer 2012
Ian Tien and Dan Maas launch SpinPunch in YC's Summer 2012 batch, building HTML5 real-time strategy games including Mars Frontier. The company develops an internal chat tool that would later become Mattermost.
Mattermost v1.0 Open-Sourced Under MIT License
SpinPunch open-sources its internal chat tool as Mattermost v1.0, positioning it as a self-hosted alternative to Slack. The release is prompted by the team's frustration with proprietary messaging vendor lock-in. GitLab community requests drive the MIT license choice over the original Apache-AGPL.
Enterprise Edition E10 Launches Open-Core Model
Mattermost introduces Enterprise Edition E10, a commercial tier offering multi-team support, LDAP synchronization, and advanced access controls. This marks the beginning of the open-core business model, separating free and paid features. E10 is priced at approximately $39/user/year.
Mattermost Raises $3.5M Seed Round from S28 Capital
Mattermost secures $3.5 million in seed funding from S28 Capital, providing the first external capital to scale the open-source messaging platform. The funding supports hiring and go-to-market efforts for the enterprise edition.
E10 Price Increase to $3.25/User/Month for New Customers
Mattermost raises Enterprise Edition E10 pricing to $3.25/user/month (billed annually) for new customers, effective October 1, 2017. Existing customers retain their original pricing. The company frames the increase as reflecting the expanded feature set added over the prior 18 months.
Mattermost Raises $20M Series A Led by Redpoint Ventures
Mattermost closes a $20 million Series A round led by Redpoint Ventures with participation from S28 Capital and Y Combinator. The funding is directed toward accelerating the product roadmap and scaling the go-to-market team. At this point, the platform sees over 10,000 server downloads per month.
YC Continuity Leads $50M Series B Round
Y Combinator's Continuity Fund leads a $50 million Series B round in Mattermost, with participation from Battery Ventures, Redpoint Ventures, and S28 Capital. Total funding reaches approximately $73.5 million. The investment signals aggressive growth ambitions as an open-source Slack alternative for security-conscious enterprises.
Community Criticizes Feature Gating in Open-Source Edition
Hacker News discussion highlights that Mattermost's open-source edition intentionally lacks basic functionality available in the paid enterprise tiers, including multi-factor authentication and guest accounts. Community members argue this undermines the "open source alternative to Slack" positioning.
COVID-19 Accelerates USAF Platform One Deployment
As tens of thousands of Air Force personnel shift to remote work, Platform One deploys Mattermost from zero to accredited in 48 hours. Within a week, 80,000 USAF personnel are on the platform, supporting over a million DoD employees. The deployment handles CUI-level communications for pre-mission paperwork, flight authorization, and post-mission forms.
Mattermost Cloud SaaS Platform Launches
Mattermost launches Mattermost Cloud, its first SaaS offering, alongside Incident Management playbooks. The cloud platform offers single-tenant dedicated infrastructure for privacy-conscious enterprises. This marks a strategic expansion beyond the self-hosted-only model that defined the company's first five years.
Mattermost v6.0 Ships with Boards and Playbooks Enabled by Default
Mattermost v6.0 launches with a refreshed UI, Boards (formerly Focalboard) and Playbooks (formerly Incident Collaboration) enabled by default. The release transforms Mattermost from a messaging tool into a broader collaboration platform, directly competing with Notion and Asana in addition to Slack.
Mattermost Government Solutions Launched for Defense Sector
Mattermost unveils Government Solutions, a dedicated offering for public sector and defense organizations with compliance controls and preferential pricing. The platform is available on NASA SEWP and other government-wide acquisition contracts. This formalizes the company's pivot toward defense and national security markets.
Mattermost v7.0 Adds Voice Calling and Screen Sharing
Mattermost v7.0 introduces three of the top five most-requested features: Collapsed Reply Threads (GA), Mobile v2.0 (beta), and native voice calling with screen sharing (beta). The voice calling feature enables one-click audio conversations without external tools, reducing dependency on third-party conferencing providers.
Mattermost Lays Off 30 Employees (15% of Workforce)
Mattermost cuts 30 employees in its first round of layoffs, representing approximately 15% of the workforce. The layoffs come amid a broader tech industry downturn and signal growing financial pressure on the company despite its $73.5M in total funding.
Second Round of Layoffs Further Reduces Workforce
Mattermost conducts a second round of layoffs in 2023, with Glassdoor reviews indicating the combined cuts reduced the workforce by nearly 50%. Employee reviews cite management transparency issues and lack of technical vision as contributing factors. The 3.3/5 Glassdoor rating reflects growing internal discontent.
Mattermost Boards Moved to Maintenance Mode and Community Support
Effective September 15, 2023, Mattermost staff stop reviewing or merging pull requests for the Boards plugin and standalone Focalboard. Boards is no longer bundled with Mattermost v9.0, and the repository is transferred to the community organization on GitHub. The decision abandons a major product pillar launched just two years earlier.
Mattermost Announces Secure SMS Alternative for National Security
Mattermost announces a joint-development program to build a secure SMS alternative for national security organizations, citing AI-based impersonation and mobile number takeover threats. The system would provide federated communications with identity verification for mission partners and law enforcement, replacing consumer apps like Signal and WhatsApp.
Mattermost Copilot AI Launches with Bring-Your-Own-LLM
Mattermost announces general availability of Mattermost Copilot, an AI assistant allowing organizations to integrate LLMs directly into their self-hosted Mattermost instance. The bring-your-own-LLM model enables multiple AI bots, call summaries, and workflow automation while maintaining data sovereignty. The feature is purpose-built for government and defense organizations subject to strict compliance requirements.
Mattermost v10 Drops MySQL Support for New Installations
Mattermost v10.0 releases with Copilot GA, Microsoft Teams integration, and a major infrastructure change: new installations using MySQL are no longer supported, requiring PostgreSQL. Existing MySQL deployments are warned of full removal in v11. The change streamlines development but forces migration for many self-hosted users.
Mattermost Revenue Reaches $33.1M with 156 Employees
Mattermost reports $33.1 million in revenue for 2024, up 59% from $20.7 million in 2023, achieved with a lean 156-person team. The revenue-per-employee ratio of approximately $212,000 suggests the post-layoff restructuring achieved efficiency goals, validating the defense-first commercial strategy.
Three Critical CVEs Disclosed in Mattermost Boards Plugin
Mattermost discloses three critical security vulnerabilities in the Boards plugin: CVE-2025-20051 (arbitrary file read via board duplication), CVE-2025-24490 (SQL injection via board reordering), and CVE-2025-25279 (arbitrary file read via board import). The irony is stark: Boards was already abandoned to community maintenance 17 months earlier, and the vulnerabilities stem from the unmaintained code.
Mattermost Launches Enterprise Advanced for Defense and Intelligence
Mattermost introduces Enterprise Advanced, a new premium tier purpose-built for defense, intelligence, and critical infrastructure organizations. The tier includes post-quantum-secure cryptography, Zero Trust security controls, and agentic AI capabilities, available July 2025. The launch solidifies the company's strategic pivot from open-source Slack alternative to defense-focused secure collaboration vendor.
Hack Club Migrates from Slack to Mattermost After Price Extortion
Hack Club, a global nonprofit coding community for teens, announces migration from Slack to Mattermost after Slack threatens to deactivate their workspace with 3 days' notice unless they pay $200,000/year (up from $5,000). The move becomes a high-profile endorsement of Mattermost's self-hosted model, though it occurs just weeks before the v11 free tier restrictions.
Mattermost v11 Launches Entry Edition with 10,000-Message Limit
Mattermost v11 introduces Entry Edition, a new free tier replacing the previous free offering, with enterprise features (AI, Boards, audit logs, SSO) but a hard 10,000-message limit for up to 100 users. Team Edition is capped at 250 users and loses GitLab SSO, Playbooks, and other features. The changes are retroactive, immediately applying to all existing installations upon upgrade.
GitLab SSO Removed from Team Edition in v11
Mattermost v11 removes the built-in GitLab SSO integration from Team Edition, eliminating the only free OAuth2 identity provider option. For years, the GitLab SSO bridge allowed self-hosted users to connect any OAuth2 server for passwordless login without the commercial edition. Affected deployments must migrate to Entry Edition (with message limits) or pay for Professional.
Playbooks Deprecated from Team Edition in v11
Mattermost v11 removes Playbooks functionality from the free Team Edition. The workflow automation feature, originally launched as Incident Collaboration in 2020 and integrated into the free tier in v6.0, now requires Entry Edition or a paid subscription. Teams relying on playbooks for incident response face a pay-or-lose-functionality ultimatum.
Team Edition User Limit Reduced from 1,000 to 250
Mattermost v11 reduces the Team Edition user limit from 1,000 to 250 activated users. The company justifies the change by noting Team Edition was 'widely over-deployed to thousands of users,' but the effect is to push mid-size organizations toward paid tiers. Organizations exceeding the limit cannot add new users.
Mattermost Omnibus Reaches End of Life with v11
The Mattermost Omnibus installer, which simplified self-hosted deployment, reaches end of life with v11. The last Omnibus release is v10.12, and GitLab will continue bundling Mattermost only through v10.11 ESR (with security updates until August 2026). This removes an easy deployment path that attracted many small organizations to the platform.
v11 Removes MySQL Support Entirely from Codebase
Mattermost v11 completely removes MySQL database support from the codebase, requiring all remaining MySQL deployments to migrate to PostgreSQL. The server throws an invalid configuration error if MySQL is configured. Combined with the v10 deprecation warning, this affects organizations with established MySQL infrastructure who face a forced migration.
Helmholtz Research Network Announces Migration Away from Mattermost
Germany's Helmholtz Association, one of the world's largest scientific research organizations, announces it will migrate away from Mattermost to Matrix after v11 restrictions deprecate the technology enabling Helmholtz ID login. The migration affects multiple major German research centers (HZDR, GFZ, DESY, GSI, UFZ, FZJ, CISPA) and highlights the institutional consequences of the free tier changes.
Community Forum Publishes Critical Response to v11 Changes
A detailed community post on the Mattermost forums documents the impact of v11 changes, arguing the Entry Edition represents a 'bait-and-switch' that violated the social contract between Mattermost and its self-hosted community. The post compiles testimonials from affected organizations and proposes alternatives including grandfathering existing deployments.
School with 2,000+ Users Loses Access to 470,000 Messages
A GitHub issue documents a school running Mattermost with over 2,000 users and 470,000 messages that loses access to years of institutional knowledge after upgrading to v11. The 10,000-message limit hides all but the most recent messages despite the data sitting in the school's own PostgreSQL database on its own servers.
Hacker News Discussion Amplifies 'Open Source Betrayal' Narrative
The ByteIota article 'Mattermost 10,000 Message Limit: Open Source Betrayal' reaches the front page of Hacker News, generating widespread discussion. Commenters characterize Mattermost as 'fake open source cosplay' and compare the retroactive data restriction unfavorably to Slack's own 90-day message limit, noting at least Slack doesn't hide data users stored on their own hardware.
Gigazine Coverage Reaches International Audience on Message Limit
Japanese technology outlet Gigazine publishes coverage of the Mattermost message limit controversy, bringing the issue to an international audience. The article emphasizes the absence of a grandfather clause or migration grace period, and contrasts the retroactive enforcement against the self-hosted model's promise of data sovereignty.
Evidence (36 citations)
D1: User Value Erosion
D2: Business Customer Exploitation
D3: Shareholder Extraction
D4: Lock-in & Switching Costs
D5: Twiddling & Algorithmic Opacity
D6: Dark Patterns
D7: Advertising & Monetization Pressure
D8: Competitive Conduct
D9: Labor & Governance
D10: Regulatory & Legal Posture
Scoring Log (4 entries)
Stripped for Phase 2 re-enrichment