True cost comparison — not just what the pricing page says
Quick Verdict
Slack saves you 100%
Best for Trello
Team messaging and collaboration hub. Free plan has a 90-day message history limit that forces upgra
Best for Slack
Atlassian's visual Kanban board tool. Free plan is limited by Power-Up restrictions, automation caps
Atlassian's visual Kanban board tool. Free plan is limited by Power-Up restricti...
Advertised
$5
/month
True Cost
$20
/month (typical)
Power-Up Limit on Free
Free plan allows only 1 Power-Up per board. Need Slack + Google Drive + Calendar? That is 3 Power-Up...
Automation Command Caps
Free: 250 command runs/mo. Standard: 1,000. Premium: 6,000. Complex automations burn through limits ...
View Restrictions
Dashboard, Timeline, Calendar, and Map views require Premium at $10/user/mo. Free and Standard only ...
10MB Attachment Limit on Free
Free plan caps file attachments at 10MB per file. Standard allows 250MB. Teams sharing design files,...
Team messaging and collaboration hub. Free plan has a 90-day message history lim...
Advertised
$0
/month
True Cost
$8
/month (typical)
90-Day Message History Limit
Free plan deletes message access after 90 days. Your team's entire knowledge base disappears quarter...
Per-User Cost at Scale
A 100-person company on Pro pays $875/mo ($10,500/yr). Business+ is $1,250/mo ($15,000/yr). The per-...
Slack Connect External Channels
Connecting with external organizations requires Pro ($8.75/user/mo) minimum. Free plan has no extern...
$7/mo annual
Slack advertises $0/mo. Trello advertises $5/mo.
Slack has 3 documented hidden fees. Trello has 4.
Slack confidence: 83%. Trello confidence: 80%.
| Metric | Trello | Slack | Winner |
|---|---|---|---|
| Advertised Price | $5/mo | $0/mo | Slack |
| True Monthly Cost | $20/mo | $8/mo | Slack |
| Hidden Fee Total | +$15/mo | +$8/mo | Slack |
| # Hidden Fees | 4 | 3 | Slack |
| Confidence Score | 80% | 83% | Slack |
| Pricing Tiers | 4 | 4 | — |
| Affiliate Program | No public affiliate program | No public affiliate program | — |
Trello advertises $5/mo and Slack advertises $0/mo. However, when you include hidden fees, Trello has 4 documented hidden fees adding +$15/mo, while Slack has 3 hidden fees adding +$8/mo. Based on true cost, Slack is typically 100% cheaper.
Trello has 4 documented hidden fees: Power-Up Limit on Free, Automation Command Caps, View Restrictions, 10MB Attachment Limit on Free. These add approximately +$15/mo on top of the $5/mo advertised price.
Slack has 3 documented hidden fees: 90-Day Message History Limit, Per-User Cost at Scale, Slack Connect External Channels. These add approximately +$8/mo on top of the $0/mo advertised price.
Choose Trello if: Team messaging and collaboration hub. Free plan has a 90-day message history limit that forces upgra. Choose Slack if: Atlassian's visual Kanban board tool. Free plan is limited by Power-Up restrictions, automation caps. The right choice depends on your team size, usage volume, and which features you need most.
This comparison is based on manual research of official pricing pages, terms of service, and user reports. Trello data has a 80% confidence score and Slack has 83%. Prices were last verified in April 2026. For the most accurate estimate, enter your specific usage in our calculator.
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