Mattermost — Open Source Slack Alternative for Team Collaboration

What Mattermost Does

• Messaging: Channels (public/private), direct messages, group messages, threads
• Voice & Video: Built-in voice and video calls with screen sharing
• Playbooks: Structured workflows for incident response, onboarding, and release processes
• File Sharing: Drag-and-drop file uploads with preview and search
• Integrations: 200+ integrations via webhooks, slash commands, and plugins
• Search: Full-text search across all messages, files, and channels
• Compliance: Message retention, compliance exports, eDiscovery, and audit logs
• Mobile: Native iOS and Android apps with push notifications
• SSO: SAML, OAuth 2.0, LDAP/AD, and GitLab authentication

Architecture

┌──────────────┐     ┌──────────────┐     ┌──────────────┐
│ Web / Desktop│────▶│  Mattermost  │────▶│  PostgreSQL  │
│ / Mobile App │     │  Server (Go) │     │  (Data)      │
└──────────────┘     └──────┬───────┘     └──────────────┘
                            │
              ┌─────────────┼─────────────┐
              │             │             │
       ┌──────┴──┐   ┌─────┴───┐   ┌─────┴───┐
       │  MinIO  │   │ Elastic │   │  SMTP   │
       │ (Files) │   │ (Search)│   │ (Email) │
       └─────────┘   └─────────┘   └─────────┘

Self-Hosting

Docker Compose

services:
  mattermost:
    image: mattermost/mattermost-team-edition:latest
    ports:
      - "8065:8065"
    environment:
      MM_SQLSETTINGS_DRIVERNAME: postgres
      MM_SQLSETTINGS_DATASOURCE: postgres://mmuser:mmpass@db:5432/mattermost?sslmode=disable
      MM_SERVICESETTINGS_SITEURL: http://localhost:8065
    depends_on:
      - db
    volumes:
      - mm-config:/mattermost/config
      - mm-data:/mattermost/data
      - mm-logs:/mattermost/logs
      - mm-plugins:/mattermost/plugins

  db:
    image: postgres:16-alpine
    environment:
      POSTGRES_USER: mmuser
      POSTGRES_PASSWORD: mmpass
      POSTGRES_DB: mattermost
    volumes:
      - pg-data:/var/lib/postgresql/data

volumes:
  mm-config:
  mm-data:
  mm-logs:
  mm-plugins:
  pg-data:

Key Features

Channels & Organization

Team: Engineering
├── #general — Team-wide announcements
├── #frontend — Frontend discussions
├── #backend — Backend discussions
├── #incidents — Active incident coordination
├── #standup — Daily standups (bot-assisted)
└── Private: #leadership — Management only

Playbooks (Workflows)

Pre-built workflows for repeatable processes:

Incident Response Playbook:
  1. Create incident channel (auto)
  2. Assign commander and communications lead
  3. Checklist: Assess severity, notify stakeholders
  4. Status updates every 30 min (reminder bot)
  5. Retrospective template (post-incident)
  6. Archive and timeline export

Release Playbook:
  1. Create release channel
  2. Feature freeze checklist
  3. QA sign-off tasks
  4. Deploy steps with verification
  5. Rollback procedures
  6. Post-release monitoring

Integrations

DevOps:
├── GitHub / GitLab — PR notifications, issue updates
├── Jira — Ticket creation from messages
├── Jenkins / CircleCI — Build notifications
├── PagerDuty — Incident alerts in channels
└── Grafana / Prometheus — Alert forwarding

Productivity:
├── Zoom / Jitsi — Video call integration
├── Google Calendar — Meeting reminders
├── Trello / Asana — Task management
├── Confluence — Doc link previews
└── Custom Webhooks — Any service

Slash Commands

/jira create [summary] — Create Jira ticket
/github subscribe owner/repo — Get PR/issue notifications
/zoom start — Start a Zoom meeting
/poll "Question" "Option 1" "Option 2" — Create a poll
/standup — Post daily standup update

Bot & API

# Post a message via webhook
curl -X POST http://localhost:8065/hooks/your-webhook-id 
  -H "Content-Type: application/json" 
  -d '{"text": "Build #123 passed ✅", "channel": "ci-notifications"}'

# REST API
curl http://localhost:8065/api/v4/users/me 
  -H "Authorization: Bearer YOUR_TOKEN"

Mattermost vs Alternatives

FAQ

Q: What's the difference between Mattermost Team Edition and Enterprise Edition? A: Team Edition is fully free and open source, covering core messaging, channels, file sharing, Playbooks, and integrations. Enterprise Edition adds enterprise features like high availability, compliance exports, SAML SSO, and AD/LDAP group sync.

Q: Can I migrate from Slack? A: Yes. Mattermost provides a Slack import tool that supports channels, message history, users, and files. The UX and keyboard shortcuts are highly similar to Slack, keeping team switching costs low.

Q: What are the server requirements? A: Up to 50 users: 2 cores, 4 GB RAM. Up to 200 users: 4 cores, 8 GB RAM. For large-scale deployments, use a high-availability cluster configuration.

Sources & Credits

• GitHub: mattermost/mattermost — 36.1K+ ⭐
• Website: mattermost.com