How Much Does Slack Actually Cost? The True Price vs Mattermost
·OSSAlt Team
slackmattermostpricingcost-analysis2026
How Much Does Slack Actually Cost? The True Price vs Mattermost
Slack's pricing page says $8.75/user/month for Pro. But the real cost? It's higher than you think.
Slack's Real Pricing (2026)
| Plan | Per-User/Month | What You Actually Get |
|---|---|---|
| Free | $0 | 90-day message history, 10 integrations, 1:1 huddles |
| Pro | $8.75 | Full history, unlimited integrations, group huddles |
| Business+ | $15 | SAML SSO, data exports, compliance |
| Enterprise Grid | Custom ($25-35) | Unlimited workspaces, HIPAA, key management |
The Hidden Costs
1. Per-Seat Pricing Adds Up Fast
| Team Size | Slack Pro/Year | Slack Business+/Year |
|---|---|---|
| 10 | $1,050 | $1,800 |
| 25 | $2,625 | $4,500 |
| 50 | $5,250 | $9,000 |
| 100 | $10,500 | $18,000 |
| 250 | $26,250 | $45,000 |
2. Guest Users Still Cost Money
- Single-channel guests on paid plans count as users
- Multi-channel guests count as full users
- External partners and contractors = more seats
3. Storage Limits
- Pro: 10 GB per user
- At 50 users = 500 GB total
- Need more? Upgrade to Business+
4. Compliance and Export
- Message export for compliance: Business+ only ($15/user)
- Data residency: Enterprise Grid only
- HIPAA: Enterprise Grid only
5. Integration Limits on Free
- Free plan: 10 integrations max
- Forces upgrade even for small teams
Mattermost Self-Hosted: The Real Cost
| Component | Monthly Cost |
|---|---|
| VPS (4 GB RAM, Hetzner) | $7 |
| Domain | ~$1 |
| Backups (Backblaze) | $1 |
| Total | $9/month |
What You Get
- Unlimited users
- Unlimited message history
- Unlimited integrations
- Unlimited file storage (limited by disk)
- Full data ownership
- Compliance export built-in
- Self-hosted = full control
Side-by-Side Cost Comparison
| Team Size | Slack Pro/Year | Mattermost Self-Hosted/Year | Annual Savings |
|---|---|---|---|
| 10 | $1,050 | $108 | $942 (90% less) |
| 25 | $2,625 | $108 | $2,517 (96% less) |
| 50 | $5,250 | $156 | $5,094 (97% less) |
| 100 | $10,500 | $192 | $10,308 (98% less) |
| 250 | $26,250 | $300 | $25,950 (99% less) |
What You Give Up
Switching to Mattermost isn't free in non-monetary costs:
| Factor | Slack | Mattermost |
|---|---|---|
| Setup time | 0 (SaaS) | 2-4 hours |
| Maintenance | None | ~1 hour/month |
| Huddles/calls | Built-in | Plugin (Jitsi/BBB) |
| App ecosystem | 2,500+ apps | 100+ plugins |
| Familiarity | Everyone knows Slack | Learning curve |
| Uptime SLA | 99.99% | You manage it |
When Slack Makes Sense
- Teams < 10 (free plan is fine)
- Heavy use of Slack Connect (cross-company channels)
- Need enterprise compliance without in-house DevOps
- Budget isn't a concern
When Mattermost Wins
- Teams > 25 (savings become significant)
- Data sovereignty requirements
- Already have DevOps capability
- Need unlimited history without paying
- Government or regulated industries
The Bottom Line
For a 50-person team, Slack costs $5,250/year (Pro) or $9,000/year (Business+). Mattermost costs $156/year — a 97% reduction.
The real question isn't cost — it's whether your team has the 2-4 hours to set it up and 1 hour/month to maintain it.
See the full Slack vs Mattermost comparison on OSSAlt — features, integrations, and deployment options side by side.