The verdict
On the data we hold, it's close: neither pulls ahead on features, a free plan or AI access. The choice comes down to how you work.
What the data says
- Both cover 3 of the 3 features we compared.
- Both have a free plan, so you can try each before you pay.
- Both have an API and an MCP server, so either works with AI employees.
- In our HR ranking, Otter.ai places 5 and Slack 3 of 27.
Side by side
| 7 points compared | ||
|---|---|---|
| Starts at | $8.33/mo | €8.25/mo |
| Free plan | Yes | Yes |
| API | Yes | Yes |
| MCP server | Yes | Yes |
| AI summary + action items | Yes | Yes |
| Guest / external access | Yes | Yes |
| Workflow automation | Yes | Yes |
| Links |
Plans and pricing
Otter.ai
- BasicFree: 300 monthly transcription minutes, 3 lifetime file imports, includes the Otter MCP server.Free
- ProPer user: 1,200 monthly minutes, 90 minutes per meeting. Annual billing shown as $8.33 per user per month.$16.99/mo/seat
- BusinessPer user: unlimited meetings, 4 hours per meeting, admin features. Annual billing shown as $19.99 per user per month.$30/mo/seat
Slack
- FreeFree forever: 90 days of message history, up to ten apps, 1:1 meetings.Free
- ProEUR 8.25 per user per month when paying monthly; unlimited history and apps; 50% off for the first three months.€8.25/mo/seat
- Business+EUR 18 per user per month when paying monthly; advanced AI and SAML single sign-on; 50% off for the first three months.€18/mo/seat
Prices as the vendors list them. They change often; the final price is on their sites.
Who each is for
Choose Otter.ai if…
Sales, recruiting, education and media teams who spend a lot of time in calls and want transcripts, summaries and action items they can search later.
Choose Slack if…
Teams of any size that need real-time messaging, channels and quick decisions in one place, and want chat connected to their CRM, project tools and alerts.
Other options worth a look
ToolCreates a shared workspace and wiki for team documentation, knowledge, and collaboration with built-in AI.HR
From $5.42/moFree plan
ToolBring teams together on an infinite whiteboard to brainstorm, diagram and run workshops in real time.HR
From $8/mo yearlyFree plan
ToolWrite and edit documents collaboratively in the browser with instant sharing and version history.HR
From €6.80/moFree plan
ToolCentralises standard operating procedures, quizzes and onboarding materials in a searchable knowledge base.HR
From $3/mo yearlyAffiliate link- ToolThe Bloom Growth Operating System: scorecard, meetings, goals and issues on one platform, the software half of the EOS/Traction category.
HR
From $299/mo
ToolAI assistant built into Zoom that generates meeting summaries, action items and automated follow-up tasks.HR
From €15.33/mo yearlyFree plan