Open-Source & Self-Hosted Alternatives to Slack & Microsoft Teams
Enterprise chat platforms charging steep monthly per-user licenses while restricting message history on free tiers.
Why Migrate Away from Slack & Microsoft Teams?
Slack caps message history to 90 days on free tiers and charges aggressive per-seat fees for teams. All communications, code snippets, and confidential business discussions remain on external infrastructure. Self-hosted chat servers give your company permanent searchable history, unlimited users, and complete security compliance.
Top 2 Recommended Open-Source Replacements
Tested and production-ready. Click any tool to view hardware specs and docker-compose configurations.
Mattermost
MIT / AGPL⭐ 32.1k+Open source, developer-first team collaboration and chat with channels, playbooks, and integrations.
✅ Advantages
- 1:1 Slack replacement
- Dedicated desktop & mobile apps
- Enterprise compliance
⚠️ Trade-offs / Limitations
- Memory usage increases with hundreds of concurrent users
Core Features
version: '3.8'
services:
postgres:
image: postgres:16-alpine
restart: unless-stopped
environment:
POSTGRES_DB: mattermost
POSTGRES_USER: mmuser
POSTGRES_PASSWORD: mmuserpassword
volumes:
- mattermost_db:/var/lib/postgresql/data
mattermost:
image: mattermost/mattermost-team-edition:latest
restart: unless-stopped
ports:
- "8065:8065"
environment:
MM_SQLSETTINGS_DRIVERNAME: postgres
MM_SQLSETTINGS_DATASOURCE: postgres://mmuser:mmuserpassword@postgres:5432/mattermost?sslmode=disable&connect_timeout=10
MM_SERVICESETTINGS_SITEURL: https://chat.yourdomain.com
volumes:
- mattermost_data:/mattermost/data
depends_on:
- postgres
volumes:
mattermost_db:
mattermost_data:🚀 5-Minute Deployment Guide
- 1Spin up a Hetzner CX22 (4GB RAM).
- 2Save docker-compose.yml and replace DB passwords.
- 3Run `docker compose up -d`.
- 4Point your DNS `chat.yourdomain.com` and setup SSL reverse proxy.
- 5Download Mattermost mobile and desktop apps and connect to your server.
Recommended VPS for Running Mattermost
CX22 (2 vCPU, 4GB RAM)
Supports dozens of team members smoothly.
View Deploy Instructions →Zulip
Apache-2.0⭐ 21.6k+The only modern team chat app with unique topic-based threading for organized asynchronous communication.
✅ Advantages
- Best-in-class async communication model
- 100% open source Apache 2.0
- Zero lost context
⚠️ Trade-offs / Limitations
- Topic-based workflow requires brief team adjustment from flat chat
Core Features
version: '3.8'
# Official Zulip Docker deployment template:
# https://github.com/zulip/docker-zulip🚀 5-Minute Deployment Guide
- 1Set up a 4GB RAM VPS.
- 2Clone `docker-zulip` repository.
- 3Configure email SMTP settings (required for invitations and notifications).
- 4Launch via Docker Compose.
Recommended VPS for Running Zulip
CX32 (4 vCPU, 8GB RAM)
Handles high volume search indexing via RabbitMQ and Postgres.
View Deploy Instructions →Quick Specification Matrix
| Tool | License | Min RAM | Min CPU | GitHub Repo | Primary Benefit |
|---|---|---|---|---|---|
| Slack & Microsoft Teams (Proprietary) | Proprietary Closed | Managed Cloud | Managed Cloud | N/A | Turnkey but vendor lock-in & paywalls |
| Mattermost | MIT / AGPL | 2 GB | 2 vCPU | mattermost/mattermost | 1:1 Slack replacement |
| Zulip | Apache-2.0 | 4 GB | 2 vCPU | zulip/zulip | Best-in-class async communication model |