AltFreeStack
ESEN
Productivitydocker-readypermissive-license100% FOSS🟢 Lightweight · ~512MB

Zulip: Open Source alternative to Slack in 2026

Zulip organizes team conversations into topic threads within each channel, cutting down on noise compared to Slack in large teams with heavy message volume.

Alternative to Slack
License Apache-2.026k starsWebsite GitHub Repository

Audit Snapshot

View notes →

  • License — Matches GitHub

  • GitHub — Active

  • Latest release — 12.3 · 22 days ago

  • Docker Compose — Partial

  • Production — Not production-tested by AltFreeStack

Zulip vs. Slack

Pros

  • Much less noise than Slack in very active channels

Things to consider

  • The topic-thread model has a learning curve

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: 100% free software on your own server, with no artificial row, project or user limits.

⚠️ This image is the legacy path: it still works, but the project now publishes a newer image on another registry/repo. Check the comment in the docker-compose before deploying.

docker-compose.yml
version: "3.9"
# NOTA: zulip/docker-zulip (Docker Hub) es la vía "legacy" — sigue soportada
# para Zulip Server 11.x, pero Zulip 12.x+ solo se publica en
# ghcr.io/zulip/zulip-server, con variables de entorno renombradas
# (DB_HOST, DISABLE_HTTPS, NGINX_WORKERS...). No cambiamos aquí la imagen
# porque migrar requiere también reescribir esas variables, y no queremos
# publicar un docker-compose con nombres de variable sin verificar contra
# la versión real del rework — mejor dejar la vía legacy que sí funciona.
services:
  zulip:
    image: zulip/docker-zulip:latest
    restart: unless-stopped
    ports:
      - "80:80"
    environment:
      - SETTING_EXTERNAL_HOST=localhost # CHANGE THIS TO YOUR DOMAIN
      - SECRETS_email_password=""
    volumes:
      - zulip_data:/data
volumes:
  zulip_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=zulip" -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
Apache-2.0
Category
Productivity
Replaces
Slack
Tech stack
PythonDjangoPostgreSQL

Under the hood

Database

PostgreSQL

Language

Python (Django)

Platforms

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

Key features

  • Topic threads within each channel
  • Powerful search across the whole history
  • Native cross-platform apps

Preview

Zulip interface preview

Public image provided by Zulip 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:80
}

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