AltFreeStack
ESEN
Productivitydocker-ready1-click-deploypermissive-licenseOpen-Core🟡 Standard · ~1GB💾 Recommended storage: 15GB

Mattermost: Open-Core alternative to Slack in 2026

Mattermost is a secure collaboration platform widely used by DevOps and government teams, with deep integrations into CI/CD pipelines and incident response.

Core is open source, but advanced features or enterprise support may be behind a paid tier — check the license.

Alternative to SlackAlternative to Microsoft Teams
License MIT39.3k starsWebsite GitHub Repository

Audit Snapshot

View notes →

  • License — Not verifiable on GitHub

  • GitHub — Active

  • Latest release — v11.11.1 · 19 days ago

  • Docker Compose — Partial

  • Production — Not production-tested by AltFreeStack

Mattermost vs. Slack

Pros

  • Widely used in regulated and government environments

Things to consider

  • The Team edition has fewer features than Enterprise

Quick Docker installation guide

Copy this docker-compose.yml, adjust the example passwords and run docker compose up -d on your server. See the full step-by-step guide →

💡 Official SaaS or self-hosted with AltFreeStack?

  • On the official cloud: $8.75/mo per user on Slack.
  • On your own VPS: the core is free to self-host on your own server — no more monthly SaaS fee, though some advanced features stay behind a paid plan.
docker-compose.yml
version: "3.9"
services:
  mattermost:
    image: mattermost/mattermost-team-edition:11.11.1
    restart: unless-stopped
    ports:
      - "8065:8065"
    environment:
      - MM_SQLSETTINGS_DATASOURCE=postgres://mattermost:mattermost@mattermost-db:5432/mattermost?sslmode=disable
    volumes:
      - mattermost_data:/mattermost/data
    depends_on:
      - mattermost-db
  mattermost-db:
    image: postgres:15-alpine
    restart: unless-stopped
    environment:
      - POSTGRES_USER=mattermost
      - POSTGRES_PASSWORD=change-me-postgres-password # REQUIRED: generate a random secret before first run
      - POSTGRES_DB=mattermost
    volumes:
      - mattermost_pg_data:/var/lib/postgresql/data
volumes:
  mattermost_data:
  mattermost_pg_data:

🚀 Deploy in 1 command

Recommended for beginners

Copy this single command and paste it into your freshly created VPS's console (Vultr, DigitalOcean...). It downloads the script, prints it to your screen so you can see exactly what it's about to do (never a blind direct pipe), and only then installs Docker if needed, writes the files with secrets already generated, and starts everything — no nano, no pasting code blocks.

curl -sSL ".../api/deploy?stack=mattermost" -o deploy.sh && cat deploy.sh && bash deploy.sh
See what this script does →

This docker-compose corresponds to an actively maintained project — last commit today.

This docker-compose not working for you? Report it on GitHub →

Technical profile

License
MIT
Category
Productivity
Replaces
Slack, Microsoft Teams
Tech stack
GoReactPostgreSQL

Under the hood

Database

PostgreSQL

Language

Go

Platforms

Web · Desktop (Mac/Win/Linux) · Mobile (iOS/Android)

Key features

  • Playbooks for incident management
  • Native CI/CD integrations
  • Configurable compliance and retention

Preview

Mattermost interface preview

Public image provided by Mattermost on its own website.

💾 Backups in 3 steps (Day 2)

As long as the ./data folder (the "volume" mapped into the container) exists on your server, your data survives any restart or container update — that's the only thing you need to back up.

1. Create a compressed backup on the server

tar -czvf backup-$(date +%F).tar.gz ./data

2. Download it to your computer

From your computer's terminal (not your server's):

scp root@YOUR_IP:~/app/backup-*.tar.gz ./

3. Restore in case of emergency

tar -xzvf backup-file.tar.gz
🌐 Connect your domain with free SSL

Step 1 — Set up the DNS

In your domain registrar's dashboard (Cloudflare, Namecheap, GoDaddy...), create a record:

Type
A
Name/Host
@ (root domain) or a subdomain, e.g. app
Content/Value
Your server's public IP

Wait 5 to 15 minutes for the record to propagate across the internet.

Step 2 — Automatic reverse proxy with Caddy

One single file, no Nginx config or manual certificates — Caddy issues and renews Let's Encrypt HTTPS on its own.

Create a file called Caddyfile:

yourdomain.com {
    reverse_proxy localhost:8065
}

Start Caddy with this command (pulls the image and runs it in the background):

docker run -d -p 80:80 -p 443:443 --name caddy --restart always -v $PWD/Caddyfile:/etc/caddy/Caddyfile -v caddy_data:/data caddy