Mattermost as a Slack Alternative
You are paying per user for Slack. Your message history disappears. Your data lives on US servers. Mattermost does everything Slack does (channels, threads, calls, integrations) without the per-seat cost or lock-in. 39K developers agree.
Why teams leave Slack
Slack charges €4.13 to €6.75 per user per month. For a 10-person team, that is €41 to €81 monthly. At 20 people, you are paying €1,620 per year.
Slack Free deletes messages after 90 days. Slack Paid deletes them after 1 year. You lose institutional knowledge just when you need it.
Data stays on US servers. For EU teams handling customer data, this creates legal friction: GDPR requires you can locate where personal data lives, and Slack makes this difficult.
Mattermost fixes all three. Unlimited message history. Flat monthly cost. EU data residency. No per-user math.
Mattermost vs Slack Side-by-Side
What you pay. What you get. Where your data lives.
Why Opsily for Mattermost
Managed hosting that puts control back in your hands.
EU Data Residency by Default
Your Mattermost data lives in German, French, or Nordic datacenters. No US servers. No data transfer questions. GDPR compliance is built in, not bolted on. Teams handling customer data sleep better.
One Price, All Users
€9 per month covers 5 users or 500 users. No per-seat multiplication as you grow. Compare that to Slack Pro at €6.75 per user annually: a 20-person team saves €1,560 per year on Mattermost. The savings compound as you hire.
Managed Operations
Nightly encrypted backups. Automated security updates. SSL certificate renewal without asking. 24/7 monitoring. Your team uses Mattermost. Opsily handles the infrastructure. That is the deal.
Built for teams who need reliability
What Mattermost actually does
Public channels. Private channels. Direct messages. Threads to keep side conversations out of the main feed. File uploads and full-text search. @ mentions. Slash commands.
Integrations: GitLab, GitHub, Jira, PagerDuty, Jenkins, Zapier. Incoming and outgoing webhooks. Custom bots. If Slack has an integration you depend on, Mattermost likely has one too.
Voice and screen sharing via the Calls plugin. Up to ~50 concurrent participants. No separate Zoom subscription.
For teams shipping regulated software, Mattermost excels: full audit trail tied to Git commits, message retention policies spanning years, deployment on infrastructure you own.
Savings per year on a 20-person team vs Slack Pro
Slack Pro at €6.75/user/month is €1,620 annually for 20 people. Opsily Mattermost at €9/month flat is €108/year. That is €1,512 in your budget every year. Add unlimited message history that never disappears, and the decision is simple.
Trust & Compliance
Security and auditability, not as an add-on. Built in.
GDPR Compliant
EU data residency guaranteed. Host in German, French, Swedish, or other EU datacenters. Your data never touches US soil. Compliance becomes one less risk to manage.
Daily Encrypted Backups
Automated nightly backups stored encrypted. Restore from any point. Disasters are handled. You focus on work, not disaster recovery.
39K+ Developers
Open-source project used at scale by GitLab, DoD, Uber, Samsung, Wargaming. Auditable code. Active maintenance. Not a startup. Not a side project.
Simple, Transparent Pricing
All plans include EU hosting, daily backups, SSL, automated updates, and 24/7 monitoring. No per-user seats. No surprise bills. Pick the size that fits your team.
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Frequently Asked Questions
What you need to know about switching from Slack to Mattermost on Opsily.
Mattermost is open-source team chat that does what Slack does—channels, threads, file sharing, integrations, voice calls—but without per-user pricing and without vendor lock-in. Slack charges €4.13 to €6.75 per user per month. Mattermost on Opsily costs €9 per month flat, regardless of team size. For teams larger than 3 people, Mattermost is always cheaper. And your data lives where you want it: German datacenters, French datacenters, or your own infrastructure.
Stop paying per user. Start paying once.
Deploy Mattermost on Opsily in under 5 minutes. EU infrastructure. GDPR-compliant by default. No credit card required.