Cal.diy vs OpenSlots
| Tagline | Open-source online appointment scheduling built on Cal.com | Minimalist appointment slot booking system with email confirmation |
| Category | Scheduling & Booking | Scheduling & Booking |
| Replaces | Calendly, Acuity Scheduling | Calendly, Acuity Scheduling |
| GitHub stars | 46k | 400 |
| Language | Nodejs | PHP |
| License | MIT | MIT |
| Self-host difficulty | 3/5 Moderate | 2/5 Easy |
| Deploy options | Docker Docker Compose Manual | Manual Docker |
| Managed hosting | ||
| Last updated | 5 days ago | 7 months ago |
| View repo | View repo |
Where each falls short
The honest trade-offs — what you give up with each, versus the proprietary tools they replace.
Cal.diy
- Self-hosted setup requires configuring PostgreSQL, email/SMTP, and OAuth providers
- Enterprise features (SAML SSO, workflows at scale, analytics) are cloud-only or require an enterprise license
- Payment collection integrations need additional third-party setup
- Admin UI for multi-tenant management is less polished than Calendly's hosted offering
OpenSlots
- No recurring appointment or subscription booking support
- Email notifications only — no SMS or push
- No calendar sync (Google/Apple/Outlook)
Bottom line
Choose OpenSlots if you want the lower-effort setup; choose Cal.diy for the larger community and ecosystem. Cal.diy has seen more recent development. Open each guide below for deploy steps and the full feature gap.