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Mattermost

Communication

Self-hosted team messaging built for security-conscious organizations — a Slack alternative.

Go / TypeScriptLicense: AGPL-3.0Level: intermediate30,000
#chat#collaboration#messaging#slack-alternative#self-hosted

About this project

Mattermost is an open-source, self-hostable messaging and collaboration platform — a Slack/Microsoft Teams alternative built for technical and security-conscious teams. It offers channels, DMs, threads, calls, integrations, and workflow automation, all on infrastructure you control.

Market opportunity

The team-collaboration market is worth $30B+. Slack and Teams charge $7–$12+ per user/month — costs that balloon for large orgs and are a non-starter for air-gapped or regulated environments (defense, finance, healthcare). Self-hosted Mattermost is purpose-built for those buyers.

Technical overview

  • Stack: Go backend (high performance, single binary), React/TypeScript web client, PostgreSQL.
  • Scale: runs tens of thousands of users on modest hardware; supports high availability and clustering.
  • Extensible: plugins, slash commands, incoming/outgoing webhooks, and a full REST API.

Who's it for

Government, defense, fintech, and any enterprise that needs chat behind its own firewall.

How to use it

Get started

Docker (preview):

docker run --name mattermost-preview -d --publish 8065:8065 mattermost/mattermost-preview

Visit http://localhost:8065, create the admin account and your first team. For production, use the PostgreSQL-backed deployment behind Nginx with TLS.

💡 How to make a business with it

How to make money with it

1. Secure-comms hosting for regulated industries. Sell managed, compliance-aligned (HIPAA/SOC2) Mattermost to clinics, law firms, and fintechs.

  • Example: 10 firms × 40 users × $5/user/month managed fee = $24k/year.

2. Integration & migration services. Charge to migrate teams off Slack, build custom bots/plugins, and connect Mattermost to internal tools.

3. Vertical collaboration product. Bundle Mattermost with industry workflows (e.g. IT incident response) and sell it as a focused SaaS.

Need technical help?

Want help setting up Mattermost, customizing it, or building your product on top of it? Knock me — let's talk.