Rocket.Chat vs Mattermost: Self-Hosted Slack Alternative

The Bottom Line

Mattermost is the better self-hosted Slack replacement for most teams. It is lighter on resources, simpler to deploy, and its interface will feel immediately familiar to anyone coming from Slack. Rocket.Chat tries to be everything — team chat, customer support, omnichannel platform — and that ambition comes at the cost of complexity and heavier resource requirements. If you just need internal team communication, pick Mattermost. If you need a unified platform that handles customer-facing live chat alongside internal messaging, Rocket.Chat earns its overhead.

What Each Platform Actually Is

Rocket.Chat is an open-source communications platform that started as a Slack clone and evolved into an omnichannel hub. It handles internal team messaging, live chat widgets for websites, integration with WhatsApp/SMS/email, and video conferencing. It runs on Node.js with MongoDB as its database. The project is backed by Rocket.Chat Technologies Ltd. and offers both a community edition and enterprise tiers.

Mattermost is an open-source team messaging platform focused squarely on replacing Slack for internal communication. It provides channels, direct messages, threads, file sharing, and integrations. It runs on Go with PostgreSQL as its database. Mattermost Inc. offers a free Team Edition and a paid Enterprise Edition.

Both are mature, actively maintained, and have large communities. The difference is scope: Mattermost does one thing well. Rocket.Chat does many things.

Feature Comparison

Feature	Rocket.Chat	Mattermost
Core messaging (channels, DMs, threads)	Yes	Yes
Omnichannel / live chat widget	Yes (built-in)	No (third-party integrations only)
WhatsApp / SMS / email integration	Yes (native)	No
Video & voice calls	Yes (Jitsi, built-in)	Yes (plugin-based Calls)
Screen sharing	Yes	Yes (via Calls plugin)
End-to-end encryption	Yes (opt-in per room)	No (TLS in transit only)
SSO / LDAP / SAML	Yes	Yes (SAML/LDAP in Enterprise)
Custom emoji & reactions	Yes	Yes
Message editing & deletion	Yes	Yes
File sharing & previews	Yes	Yes
Threaded conversations	Yes	Yes
Slash commands & bots	Yes	Yes
Webhooks (incoming/outgoing)	Yes	Yes
App marketplace / plugins	Yes (marketplace)	Yes (plugin system)
Mobile apps (iOS/Android)	Yes	Yes
Desktop apps	Yes (Electron)	Yes (Electron)
Guest access	Yes	Enterprise only
Message read receipts	Yes	Enterprise only
Compliance / message export	Enterprise	Enterprise
Federation (server-to-server)	Yes (Matrix bridge)	No
Database	MongoDB	PostgreSQL
Primary language	Node.js / TypeScript	Go

Docker Compose: Rocket.Chat

Rocket.Chat requires MongoDB configured as a replica set. This is non-negotiable — the application will not start without oplog access.

Create a docker-compose.yml:

services:
  rocketchat:
    image: registry.rocket.chat/rocketchat/rocket.chat:8.1.1
    restart: unless-stopped
    environment:
      - MONGO_URL=mongodb://mongodb:27017/rocketchat?replicaSet=rs0
      - MONGO_OPLOG_URL=mongodb://mongodb:27017/local?replicaSet=rs0
      - ROOT_URL=http://localhost:3000
      - PORT=3000
      - DEPLOY_METHOD=docker
    ports:
      - "3000:3000"
    volumes:
      - rocketchat_uploads:/app/uploads
    depends_on:
      mongodb:
        condition: service_healthy
    networks:
      - rocketchat

  mongodb:
    image: mongodb/mongodb-community-server:8.0-ubi8
    restart: unless-stopped
    command: --oplogSize 128 --replSet rs0
    volumes:
      - mongodb_data:/data/db
    healthcheck:
      test: >
        mongosh --quiet --eval "
          try { rs.status().ok } catch(e) {
            rs.initiate({_id:'rs0', members:[{_id:0, host:'mongodb:27017'}]}).ok
          }"
      interval: 10s
      timeout: 10s
      retries: 5
      start_period: 30s
    networks:
      - rocketchat

volumes:
  mongodb_data:
  rocketchat_uploads:

networks:
  rocketchat:

Create a .env file:

# Change ROOT_URL to your actual domain in production
# ROOT_URL=https://chat.example.com

Start the stack:

docker compose up -d

MongoDB needs a few seconds to initialize the replica set on first boot. Watch the logs:

docker compose logs -f rocketchat

Once you see SERVER RUNNING, visit http://localhost:3000. The setup wizard walks you through creating the admin account, organization name, and server registration (registration is optional — skip it to stay fully self-hosted).

Docker Compose: Mattermost

Mattermost uses PostgreSQL and has a straightforward deployment. The official repository provides a well-structured setup.

Create a docker-compose.yml:

services:
  mattermost:
    image: mattermost/mattermost-team-edition:10.5.1
    restart: unless-stopped
    pids_limit: 200
    security_opt:
      - no-new-privileges:true
    tmpfs:
      - /tmp
    environment:
      - TZ=UTC
      - MM_SQLSETTINGS_DRIVERNAME=postgres
      - MM_SQLSETTINGS_DATASOURCE=postgres://mmuser:mmuser_password@postgres:5432/mattermost?sslmode=disable&connect_timeout=10
      - MM_BLEVESETTINGS_INDEXDIR=/mattermost/bleve-indexes
      - MM_SERVICESETTINGS_SITEURL=http://localhost:8065
    ports:
      - "8065:8065"
      - "8443:8443/udp"
      - "8443:8443/tcp"
    volumes:
      - mattermost_config:/mattermost/config
      - mattermost_data:/mattermost/data
      - mattermost_logs:/mattermost/logs
      - mattermost_plugins:/mattermost/plugins
      - mattermost_client_plugins:/mattermost/client/plugins
      - mattermost_bleve:/mattermost/bleve-indexes
    depends_on:
      postgres:
        condition: service_healthy
    networks:
      - mattermost

  postgres:
    image: postgres:16-alpine
    restart: unless-stopped
    security_opt:
      - no-new-privileges:true
    pids_limit: 100
    read_only: true
    tmpfs:
      - /tmp
      - /var/run/postgresql
    environment:
      - TZ=UTC
      - POSTGRES_USER=mmuser
      - POSTGRES_PASSWORD=mmuser_password
      - POSTGRES_DB=mattermost
    volumes:
      - postgres_data:/var/lib/postgresql/data
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U mmuser -d mattermost"]
      interval: 10s
      timeout: 5s
      retries: 5
    networks:
      - mattermost

volumes:
  mattermost_config:
  mattermost_data:
  mattermost_logs:
  mattermost_plugins:
  mattermost_client_plugins:
  mattermost_bleve:
  postgres_data:

networks:
  mattermost:

Start the stack:

docker compose up -d

Visit http://localhost:8065. Create your first account — the first user automatically becomes the system administrator. No setup wizard. No registration prompts. You are in.

Important: Change mmuser_password to a strong password before deploying to production. Set MM_SERVICESETTINGS_SITEURL to your actual domain.

Installation Complexity

Mattermost wins here decisively.

Mattermost is a single binary backed by PostgreSQL. The Docker Compose file is clean. docker compose up -d, create an account, done. PostgreSQL is the most battle-tested relational database on earth. If you have run any web application before, you already know how to back up and maintain it.

Rocket.Chat requires MongoDB with replica set mode enabled. MongoDB replica sets add operational complexity — you need the oplog configured correctly, and the health check must initialize the replica set on first boot. The compose file is more involved. The setup wizard has more steps. It works, but there are more moving parts that can break.

Time from docker compose up to a working chat room:

• Mattermost: ~2 minutes
• Rocket.Chat: ~5 minutes (MongoDB replica set initialization + setup wizard)

Performance and Resource Usage

Resource	Rocket.Chat	Mattermost
RAM (idle, small team)	~800 MB - 1.2 GB	~300-500 MB
RAM (50 users, active)	~1.5-2.5 GB	~600 MB - 1 GB
CPU (idle)	Low-Medium	Low
CPU (active messaging)	Medium	Low
Disk (application)	~1 GB	~500 MB
Database engine	MongoDB (memory-hungry)	PostgreSQL (efficient)
Minimum recommended RAM	2 GB	1 GB
Recommended RAM (production)	4 GB+	2 GB+

Rocket.Chat’s Node.js runtime and MongoDB backend consume significantly more memory than Mattermost’s Go binary and PostgreSQL. On a small VPS with 2 GB RAM, Mattermost runs comfortably. Rocket.Chat will struggle under load at that level.

Mattermost’s Go backend is also more predictable under load. Node.js can exhibit garbage collection pauses that cause brief latency spikes during heavy usage. For teams under 50 users, neither matters. Above that, Mattermost scales more gracefully on modest hardware.

Community and Ecosystem

Rocket.Chat has a large community (39k+ GitHub stars), an active marketplace for apps and integrations, and strong international adoption. Documentation is comprehensive but sometimes lags behind releases. The omnichannel features attract businesses that need customer support tooling alongside internal chat.

Mattermost has a similarly large community (31k+ GitHub stars), an extensive plugin ecosystem, and strong adoption in security-conscious organizations (government, defense, finance). Documentation is excellent — consistently up to date and well-organized. The DevOps and developer tooling integrations (Jira, GitHub, GitLab, Jenkins) are particularly polished.

Both projects are actively maintained with regular releases. Mattermost follows a predictable monthly release cycle. Rocket.Chat releases are less predictable but frequent.

Use Cases

Choose Rocket.Chat If…

• You need omnichannel support — live chat widgets on your website, WhatsApp integration, email routing to chat agents
• You want end-to-end encryption for sensitive conversations
• You need federation between multiple chat servers (Matrix bridge support)
• You are replacing both Slack (internal) and Intercom/Zendesk (customer-facing) with a single platform
• You need a unified communications hub, not just team messaging

Choose Mattermost If…

• You want a clean Slack replacement for internal team communication
• You are running on limited hardware (1-2 GB RAM VPS)
• You want the simplest possible deployment and maintenance
• Your team already uses PostgreSQL and you want to keep your database stack consistent
• You need strong DevOps integrations (CI/CD, incident response, developer workflows)
• You prioritize a Slack-like UX that your team can adopt without training

Final Verdict

Mattermost is the right choice for most self-hosters. It does one thing — team messaging — and does it exceptionally well. The deployment is simple, the resource usage is modest, the Slack-like interface requires zero training, and PostgreSQL is a database you already know how to operate. For a team that just needs to stop paying for Slack, Mattermost is the answer.

Rocket.Chat earns its place when you need more than team chat. If your business handles customer conversations alongside internal messaging — live chat, WhatsApp, email routing — Rocket.Chat consolidates those into one platform. That is genuinely valuable. But if you do not need omnichannel, you are paying the complexity and resource tax for features you will never use.

Pick Mattermost unless you have a specific reason to pick Rocket.Chat. You probably know if you do.

Related

• Best Self-Hosted Communication & Chat Apps
• How to Self-Host Mattermost
• How to Self-Host Rocket.Chat
• Matrix vs Mattermost
• Self-Hosted Alternatives to Slack
• Docker Compose Basics
• Reverse Proxy Setup