Mattermost vs. Slack: Why Your Team Should Self-Host Chat

Team chat is essential infrastructure. If your team communicates through WhatsApp groups, you are mixing business discussions with personal messages on a platform you do not control. Slack solves the platform problem but creates a new one: your entire communication history lives on someone else's server. Mattermost solves both problems.

What Mattermost Is

Mattermost is an open-source, self-hosted team chat platform designed as a Slack alternative. It looks and works like Slack: channels organised by topic, direct messages, file sharing, threaded replies, and search. The difference is that Mattermost runs on your server, and you control every aspect of it.

The free team edition supports unlimited users, unlimited message history, and unlimited integrations. There is no per-user pricing, no message retention limits, and no data storage on third-party servers. Your messages are your data, on your hardware.

The Real Cost of Slack

Slack's free plan limits you to the most recent 90 days of messages. After that, messages disappear. For a business that uses chat as institutional memory, this is a dealbreaker. Slack's paid plans start at 7.25 US dollars per user per month. A 15-person team pays over 1,300 dollars per year for chat.

That money buys you a hosted service that stores your messages on Amazon Web Services. If Slack has an outage, your team cannot communicate. If Slack changes its pricing, you pay more or migrate. If Slack's search goes down, you cannot find last month's decision about the client proposal.

What Mattermost Gives You That Slack Does Not

• Unlimited message history: Every message, forever, searchable. The institutional knowledge of your business does not expire after 90 days.
• Data ownership: Messages are stored in your PostgreSQL database on your server. Export them, back them up, or migrate them at any time.
• No per-user fees: One server, one deployment, unlimited users. The only cost is the server hardware.
• On-premises compliance: For businesses in regulated industries or those that handle sensitive client data, having chat on your own infrastructure simplifies compliance.
• Custom branding and theming: Mattermost can look exactly like your internal tools, with your logo, colours, and custom emoji.

The Trade-offs

Self-hosting Mattermost means you manage the server, apply updates, and handle backups. This is not zero effort, but it is predictable effort. A Mattermost server with 15 active users runs comfortably on a 4GB VPS with PostgreSQL. Weekly database backups take five minutes to configure and run automatically.

Slack handles uptime, updates, and infrastructure for you. That convenience is what you pay for. For teams that value data ownership and long-term cost control, Mattermost is the better choice. For teams that want zero operational responsibility, Slack is simpler. The question is whether simplicity is worth 1,300 dollars per year and ceding control of your communication data.

Deploying Mattermost

Mattermost deploys via Docker Compose in about 10 minutes. The official Docker image includes everything needed. Connect it to your existing PostgreSQL instance or let the Compose file spin one up. Add Mattermost behind your reverse proxy with SSL, integrate with Authelia for single sign-on, and connect the mobile and desktop apps. Your team will not notice the difference from Slack.

VPS1 deploys Mattermost as part of your managed stack. We handle the setup, SSO integration, and ongoing maintenance.