Mattermost vs Slack: Which Team Chat Platform Fits Your Budget?
Slack dominates the SaaS market. Mattermost is open-source, cheaper at scale, and keeps your data under your control. We compare them head-to-head: cost, features, lock-in risk, and the migration path.
Feature-by-Feature Comparison
How Slack and Mattermost stack up.
Slack pricing as of Aug 2026. Mattermost managed includes Opsily infrastructure costs. Both platforms support user imports from each other.
Real savings from a team of 10 that switched from Slack to managed Mattermost.
A 10-person team on Slack Pro pays €990/year. On Mattermost managed, €120/year. The math compounds: 100 people saves €99,000 annually.
The cost problem Slack does not solve
Slack is built for startups and small teams. The UX is polished. Setup takes minutes. You get 24/7 support.
But Slack's per-user model breaks down:
- At 100 users: €825/month (€8.25 Pro) or €1,800/month (€18 Business+)
- At 500 users: €4,125/month (Business+) becomes a line-item budget fight
- Message history disappears after 90 days on Free/Pro. Compliance teams, legal, and support orgs need everything archived
- GDPR-conscious companies struggle: EU data residency is Enterprise+ only, and Slack still controls your encryption keys
These are not edge cases. They are everyday problems at scale.
Mattermost solved one problem; infrastructure created another
Mattermost is the answer to the Slack problem. It is open-source. You own the code. Your data never leaves your infrastructure. The license is MIT: no vendor lock-in.
But self-hosting Mattermost meant hiring:
- PostgreSQL expertise (setup, replication, failover)
- Linux administration (OS patches, certificate renewal)
- SRE on-call rotation (4 AM outages because the database filled up)
- Backup recovery drills (monthly restore tests)
The infrastructure tail wagged the dog. Many teams tried Mattermost and gave up because running it was harder than writing the checks to Slack.
Managed Mattermost: Slack ease plus Mattermost economics
Managed Mattermost hosting flips the equation. Opsily handles:
- PostgreSQL setup, replication, and automatic failover
- OS patches, SSL renewal, certificate management
- Daily encrypted backups (tested monthly)
- Monitoring 24/7; escalation to on-call
- Horizontal scaling as you grow from 50 to 10K users
- Multi-region failover and disaster recovery
You never think about infrastructure again. You log in and invite your team.
Mattermost becomes not just cheaper than Slack; it becomes easier than Slack for teams that value data control.
Migration is not the friction point
Teams worry: "Will we lose message history? What about integrations?"
Answer: mmetl (Mattermost's migration tool) exports every message, file, thread, and emoji reaction from Slack. It is lossless. The import takes 2-4 hours per 10K messages.
Slack integrations are usually just webhooks. Mattermost supports the same webhooks. Custom Slack apps (Workflow Builder, etc.) require manual rebuild on Mattermost, but most teams find Mattermost's native automation more powerful anyway.
The real decision point is not technical. It is financial: do you want to spend €99K/year on per-user chat, or reinvest that in hiring?
Why Opsily for Managed Mattermost?
We manage the infrastructure. You manage your team.
Cost stays predictable
Flat monthly bill. No surprise per-user charges. A 500-person team on Opsily costs the same as a 50-person team. Budgets are final; scaling is guilt-free. You control the infrastructure spend independently from headcount.
Your data, your control
Choose your datacenters: Frankfurt, Amsterdam, Helsinki, London, Paris, Stockholm, or US. GDPR compliance is built-in. You export data anytime via standard formats. No lock-in to Opsily, no lock-in to Slack. Your Mattermost instance is yours.
Operations disappear
Automated daily backups with encryption at rest and in transit. Kernel patches, database failover, certificate renewal, and security monitoring handled automatically. 24/7 alerts escalate to our team. You never wake up at 3 AM.
Built for teams who need reliability
Transparent, All-Inclusive Mattermost Hosting
All plans include 24/7 monitoring, daily backups, SSL certificates, and your choice of datacenters. No setup fees. No overage charges. Scale up or down anytime.
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Enterprise Trust and Compliance
Security and compliance built into every plan.
GDPR Compliant by Design
Your data stays in your chosen region. No multi-tenant sharing. Full customer control over encryption keys, backup locations, and data deletion.
ISO 27001 Infrastructure
Opsily's datacenters meet international security standards for information confidentiality, integrity, and availability. Annual third-party audits included.
Encrypted Backups at Rest and in Transit
All backups encrypted with AES-256. Monthly restore drills ensure zero data loss. Recovery point objective: less than 1 hour.
SOC 2 Type II Audited
Our hosting infrastructure and operational processes pass annual SOC 2 audits by independent security firms. Reports available to enterprise customers.
Multiple Datacenters Across Europe
Frankfurt, Amsterdam, Helsinki, London, Paris, Stockholm. Choose based on your compliance requirements. Data never moves unless you request it.
Frequently Asked Questions
Everything you need to know about switching from Slack to Mattermost and running it on Opsily.
Yes, at scale. Slack charges €8.25 per user per month (Pro tier) or €18 per user per month (Business+). A 100-person team on Slack Pro costs €825/month or €9,900/year. The same team on Mattermost managed is €100/month or €1,200/year. For a 500-person team, Slack Business+ runs €7,500/month; Mattermost managed stays under €400/month. The gap widens as you grow. For small teams (under 20 people), the savings are modest, but Mattermost wins on features (unlimited message history, full data control).
Ready to cut your chat bill by 90%?
Start your Mattermost instance on Opsily today. No credit card required for the 7-day trial. Migration support and full data import included.