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DayOtter vs Cal.com
Cal.com was the open-source scheduler for years - then moved its core to a closed repo in 2026, keeping only a stripped-down fork with the commercial features removed. DayOtter is the genuinely open alternative: AGPLv3, the whole product, AI included.
For years Cal.com was the open-source scheduler developers loved - API-first, self-hostable, strong routing. In April 2026 it moved its production codebase to a closed repository (citing AI), keeping a separate MIT fork, "Cal.diy", with the commercial features - Organizations, Teams, Routing, Workflows, Instant Booking - removed. So the open version is now a demo, and the real product is closed.
DayOtter took the opposite path. The whole product - teams, routing, workflows, and all of Otter's AI - is AGPLv3 and self-hostable, free forever. And it's built around Otter, a confirm-first assistant that books, protects focus, and handles overflow at no per-minute cost (Cal.com's AI was a usage-priced voice add-on).
What Cal.com does well
Cal.com's API and app ecosystem are mature, and their hosted product is polished. If you want a managed scheduling API and don't mind that the core is now closed, it's an established choice.
| DayOtter | Cal.com | |
|---|---|---|
| License | AGPLv3 - genuinely open | Core closed (2026); stripped MIT fork |
| Self-host the whole product | Yes - teams, routing, AI, all of it | Fork has commercial features removed |
| Generous free plan | Yes | Yes |
| AI assistant | Otter, included - chat + confirm-first | Cal.ai was usage-priced voice (~$0.29/min) |
| Time protection | Focus auto-scheduling + running-late alerts | None |
| Routing forms | Yes | Yes (flagship) |
| Team round-robin | Weighted | Weighted |
| Developer platform / API | Keys & webhooks | Deeper, platform API |
| Enterprise (SSO/SCIM) | On the roadmap | On Orgs tier |
| Ease of setup | Calm, opinionated | Powerful, more to configure |
Why teams pick DayOtter
Still genuinely open source
Cal.com moved its core to a closed repo and stripped the commercial features out of its open fork. DayOtter is AGPLv3 - teams, routing, workflows, and all of Otter's AI are in the open core, self-hostable and free forever. Not a demo.
The assistant is the product, not an add-on
Talking to Otter is the main way to get things done - book, reschedule, protect focus, confirm-first, at no metered cost. Cal.com's AI was a separate voice product billed by the minute.
Time protection built in
Otter finds open time and holds it for deep work, and warns your next meeting when you're running behind - Reclaim/Motion territory Cal.com never touched.
Choose Cal.com if
You want a mature, managed scheduling API and app ecosystem, and you're comfortable that the core is now closed.
Choose DayOtter if
You want a genuinely open, self-hostable platform - the whole product, AI included - with a proactive assistant and time protection built in.
Questions
Didn't Cal.com go closed source?
Yes - in April 2026 Cal.com moved its production code to a closed repository and kept only a stripped MIT fork with the commercial features (Orgs, Teams, Routing, Workflows) removed. DayOtter stayed open: AGPLv3, the whole product self-hostable.
Is DayOtter really fully open source?
The core - everything except a small cloud-only infrastructure layer (managed keys, SSO, white-label) - is AGPLv3 and self-hostable for free, including every AI feature. See our docs on editions and the enterprise boundary.
Can I self-host DayOtter?
Yes - it ships with Docker/compose and unlocks every Pro feature for free when self-hosted. No license key, no billing.