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Mattermost

✓ Verified FOSSAGPL-3.0
Top open-source alternative to Slack

Mattermost is an open-source Slack alternative built for technical and security-conscious organizations. It provides 1:1 and group messaging, threaded discussions, audio calls, integrations, and compliance exports.

Tech StackGo, React, Redux
Self-Host DifficultyMedium
License ModelAGPL-3.0
GitHub Repositorymattermost/mattermost

Recommended VPS & Hardware Sizing

Estimated Hosting: $10 - $15/mo (e.g. Hetzner CPX21 or Linode)
Min RAM:2 GB
Rec RAM:4 GB
Compute:2 vCPU
Disk Space:25 GB SSD

Mattermost vs Slack Comparison Matrix

Evaluation CriteriaMattermost (Open Source)Slack (Proprietary)
Message HistoryUnlimited (Your Database)Limited to 90 Days on Free
Compliance & SecurityAir-gapped / HIPAA readyShared Public Cloud
Cost per 100 Users$0 / Server Cost Only$875 - $1,500 / month
INTERACTIVE TCO MODELEstimated Rate: $12/user/mo

Financial Impact: Migrating from Slack to Self-Hosted Mattermost

Detailed Stack Calculator →
5 Users (Early Startup)50 Users (Scaleup)200 Users (Enterprise Org)
Slack (Cloud SaaS)Per-Seat Tax
$3,600per year ($300/mo)
3-Year Spend:$10,800

* Excludes enterprise SSO add-ons & usage overages

Mattermost (Self-Hosted)Zero Per-Seat Fee
$120per year ($10/mo Linux VPS)
3-Year Compute:$360

* Commodity Hetzner / DigitalOcean compute instance

Cumulative 3-Year ROI+$10,440Net savings across 36 months (97% reduction)
Annual Free Cash:+$3,480/yr
Need C-Level Buy-In? Generate an instant ROI proposal memo to present to your CTO or CFO.

Core Capabilities & Features

✓Full Message History Retention
✓End-to-End Control
✓Custom Slash Commands
✓Mobile & Desktop Apps

Self-Host Mattermost with Docker Compose

Tweak configuration ports, secrets, and volumes live. Download or copy your ready-to-run container file:

1-Click Docker Compose Generator

Generate production-ready container definitions with customizable ports and volumes.

MattermostAGPL-3.0

Open-source, self-hosted collaboration platform for high-security teams

Difficulty: Medium39,317 ⭐
Configure Parameters
docker-compose.mattermost.yml
version: "3.8"
services:
  mattermost:
    image: mattermost/mattermost-team-edition:latest
    container_name: mattermost-app
    restart: unless-stopped
    ports:
      - "${PORT:-8065}:8065"
    environment:
      MM_SQLSETTINGS_DRIVERNAME: postgres
      MM_SQLSETTINGS_DATASOURCE: postgres://mmuser:${DB_PASSWORD:-mm_pwd}@postgres:5432/mattermost?sslmode=disable&connect_timeout=10
    depends_on:
      - postgres
  postgres:
    image: postgres:14-alpine
    container_name: mattermost-postgres
    restart: unless-stopped
    environment:
      POSTGRES_USER: mmuser
      POSTGRES_PASSWORD: ${DB_PASSWORD:-mm_pwd}
      POSTGRES_DB: mattermost
    volumes:
      - mm_pg_data:/var/lib/postgresql/data
volumes:
  mm_pg_data:

Frequently Asked Questions: Self-Hosting Mattermost

How do I self-host Mattermost using Docker Compose?

You can deploy Mattermost (mattermost/mattermost) on any Linux server by copying the docker-compose.yml template on this page, configuring your desired host port and persistent volume directory, and running 'docker compose up -d'.

How does Mattermost compare to Slack?

Mattermost is an open-source, self-hosted alternative to Slack built with Go, React, Redux. Unlike Slack ($8.75 - $15 / user / month), Mattermost has zero per-user licensing fees and keeps 100% of your data on your own infrastructure.

What are the minimum VPS RAM and CPU requirements for Mattermost?

For production self-hosting (Medium difficulty tier), we recommend at least 4 GB RAM (minimum 2 GB), 2 vCPU, and 25 GB SSD storage, which typically costs $10 - $15/mo (e.g. Hetzner CPX21 or Linode).

Is Mattermost free for commercial business use under the AGPL-3.0 license?

Yes. Distributed under the AGPL-3.0 license, Mattermost can be self-hosted internally by businesses and engineering teams of any size without per-seat royalties.

README INTEGRATION // REPO EMBED

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