Mattermost | Collaboration Platform for Mission Critical Work | WarmIndex

Mattermost is an open-source, self-hosted collaboration platform that provides secure messaging, workflows, and integrations for technical and mission-critical teams.

🚀 Overview

Mattermost is a secure, open-source alternative to Slack and Microsoft Teams, designed for teams that require full control over their communication infrastructure. It enables self-hosted deployments on-premises or in private clouds, ensuring data sovereignty, compliance, and resilience in high-stakes environments like defense, cybersecurity, and DevOps.

The project solves the problem of relying on SaaS tools that may lack security, availability during outages, or compliance with regulations like GDPR, HIPAA, or FIPS. It's built for developers, security operations centers (SOCs), incident response teams, and enterprises handling sensitive data.

Founded by former Slack engineers in 2015, Mattermost was created to deliver an open platform that accelerates mission-critical workflows with integrations, AI, and custom extensibility while maintaining operational sovereignty.

✨ Key Features

Secure, threaded messaging with channels, direct messages, and file sharing (granular permissions, compliance auditing)
Deep integrations with GitHub, Jira, PagerDuty, and 1,000+ apps; custom plugins and bots
Playbooks for incident management, checklists, and automated workflows
Real-time voice/video calling, screen sharing, Kanban boards, and AI-powered Copilot for summarization
Upcoming: Enhanced federated comms, zero-trust security, and air-gapped support in Enterprise Advanced

🛠 Tech Stack

Frontend: React, TypeScript, SCSS
Backend: Go (Golang), single Linux binary
Database: PostgreSQL, MySQL
Cache: Redis
Auth: SAML, OIDC, LDAP, MFA, custom
Hosting: Self-hosted (Docker, Kubernetes, Helm), Mattermost Cloud (SaaS)

👥 Who Is This For?

This project is useful for:

Developers who want to integrate chat with CI/CD pipelines and Git workflows
Teams looking for compliant, self-hosted collaboration in regulated industries
Indie makers building secure internal tools or open-source projects

📸 Screenshots / Demo

Live demo: https://mattermost.com/sign-up (1-hour preview environment)
GitHub: https://github.com/mattermost/mattermost

🔥 Project Status

🟢 Actively building

Last updated: 2026-03-24

❓ FAQ

Is this project free?

Freemium / Open Source Team Edition is free forever for unlimited users. Paid subscriptions (Professional, Enterprise) start from contact sales, offering advanced features, support, and scalability.

Is the source code available?

Yes — https://github.com/mattermost/mattermost

Can I contribute?

Yes — report issues, submit PRs on GitHub, contribute to plugins via mattermost-community org, join forums at forum.mattermost.com, or provide feedback on roadmap.