Mattermost

What is Mattermost?

Mattermost is an open-source, self-hosted collaboration platform designed for secure team messaging, workflow automation, and mission-critical operations, serving as a Slack alternative with full data control. It emphasizes compliance, integrations, and deployment flexibility for DevSecOps, cybersecurity, and operational teams.

Key Features

Mattermost supports threaded messaging, 1:1/group chats, audio/video calls with screen sharing, Kanban boards (Mattermost Boards), and AI agents for decision support and task automation.
It includes playbook templates for repeatable processes, deep integrations with GitHub, GitLab, Jira, ServiceNow, SIEM/SOAR tools, and video systems, plus notification customization and search across messages/files.
Security features cover E2EE options, RBAC, SSO (SAML/LDAP/OAuth), GDPR/HIPAA/SOC 2/ISO compliance, and air-gapped/DDIL (disconnected/denied/intermittent/limited) environments.

Latest Version: Mattermost v11.3 (January 2026)

The release of version 11.3 introduces several powerful features aimed at enhancing security, AI-driven workflows, and overall team productivity.

What’s New in v11.3

Burn-on-Read Messages (Enterprise Advanced): This new feature allows for the automatic deletion of sensitive messages after a configurable time interval. Admins can set how long a message remains visible after being opened (from one minute to eight hours) and how long it exists if never opened. Burn-on-read messages are marked with a 🔥 fire icon and support file attachments, mentions, and persistent notifications.

Universal MCP Connector: Mattermost now ships with a universal Model Context Protocol (MCP) connector that enables Mattermost Agents to connect to both internal and external MCP servers. This allows agents to interact with external systems like Jira, GitLab, and GitHub, unlocking powerful AI-driven workflows while maintaining enterprise-grade control.

Easy Guest Login: Guests can now join channels by logging in with a magic link, requiring no username or password. This feature is valuable for broad coalitions, emergency response efforts, and cross-agency collaboration where participants need immediate access without hurdles.

Intune MAM Support: Mattermost now supports Microsoft Intune Mobile Application Management (MAM), delivering strong mobile security without compromising productivity. Controls such as PIN enforcement, screenshot blocking, and secure file previews help keep sensitive data inside approved environments.

Multi-Window Plugin Support: Users can now pop out supported right-hand side plugins (like Boards, Playbooks checklists, and Agents) into their own separate windows while continuing to navigate channels in the main interface, improving multitasking capabilities .

Korean Language Support: Mattermost now offers full Korean language support, making the platform more accessible for Korean-speaking teams.

Core Features and Capabilities

Mattermost offers a comprehensive set of features for team collaboration, with a particular focus on technical workflows and enterprise requirements.

Core Messaging Features

Collaboration Tools

Voice and Video Calls: Built-in 1-on-1 voice calls with screen sharing on professional plans; group video calls (approximately 15 participants) available through plugins or integrations like Jitsi

Guest Accounts: Invite external collaborators with limited access permissions

Markdown Support: Format messages with rich text, code blocks, and tables

Mobile and Desktop Apps: Native applications for iOS, Android, Windows, macOS, and Linux

Enterprise Security Features

Authentication: Single Sign-On (SSO) with SAML 2.0, OAuth 2.0, LDAP/Active Directory integration, and multi-factor authentication (MFA) enforcement

Compliance: Message export, data retention policies, audit logs, and eDiscovery reporting

Deployment Flexibility: Self-hosted on-premises, private cloud, or Mattermost Cloud (SaaS)

Air-Gapped Deployment: Support for completely isolated networks with no internet connectivity, essential for military and intelligence applications

Open Source Auditability: Full code access for independent security verification and penetration testing

Deployment and Technical Requirements

Mattermost’s self-hosted nature gives organizations complete control over their data and infrastructure.

System Requirements

User Count—>Recommended Specifications
Up to 1,000 users—>1 vCPU core, 2GB RAM
Production environments—>2+ CPU cores, 4-8GB RAM, 20GB+ storage

Software Requirements

Operating System: Ubuntu 22.04/24.04 LTS, Debian 12, or other Linux distributions

Database: PostgreSQL 12+ (recommended) or MySQL 8.0+

Web Server: Nginx recommended as reverse proxy for production deployments with 200+ users

Network: Ports 80/443 for HTTP/HTTPS, port 8065 for direct Mattermost access

Pros and Cons from User Reviews

Based on verified user reviews from Gartner Peer Insights and Software Advice.

What Users Love

Data Control & Sovereignty: Full control over data with self-hosted deployment options, particularly valued by government and defense organizations.

Cost-Effective: Free version supports unlimited users, making it extremely affordable compared to proprietary alternatives.

Developer-Friendly: Excellent DevOps tools, integrations with CI/CD pipelines, and code snippet sharing.

Ease of Deployment: Users rate deployment 4.5/5, noting straightforward installation on Linux servers

Unlimited Channels: Ability to create unlimited communication channels under one roof.

Common Drawbacks

No Built-in Video Conferencing: Lacks native group video calling; requires integration with external apps like Jitsi or Zoom

Thread Management: Some users report that threaded conversations can become disorganized compared to competitors

Mobile Plugin Limitations: Plugins often don’t work in the mobile app

Update Challenges: Updates can sometimes cause configuration issues, and user preferences occasionally get reset

Notification Bugs: Some users experience missed notifications or delayed alerts

Government and Sovereign Use Cases

Mattermost is particularly well-suited for European government agencies seeking Microsoft Teams alternatives due to data sovereignty concerns and GDPR compliance requirements. Key advantages include:

Complete data residency within EU borders through self-hosted deployment

Protection from US CLOUD Act and foreign surveillance laws

Air-gapped deployment capability for classified communications

Open source auditability enabling independent security verification

Editions & Licensing

Mattermost Entry A new free, self-hosted, feature-rich edition for small teams, providing access to premium features (Playbooks, Boards) with usage limits.

Enterprise Edition Paid subscriptions designed for larger organizations requiring advanced security, auditing, and scalability.

Licensing: The core platform is open-source (MIT/AGPLv3), with enterprise features being proprietary.- Integration with Microsoft 365 for hybrid deployments

Deployment Options

Self-host via Docker, Kubernetes, Helm, or traditional installs on Linux (e.g., Ubuntu); supports clustering for high availability, load balancing, and scaling to thousands of users.
Free open-source edition (MIT license) has no user/message limits; Enterprise adds advanced clustering, compliance reporting, and plugins.
Backup strategies include database dumps (PostgreSQL/MySQL), file storage snapshots, and remote replication for reliability.