Calendly is a great scheduling app. But its API was designed as an afterthought to its UI. If you need programmatic scheduling — creating events via API, embedding booking into your own product, or taking payments at booking time — you need a scheduling API, not a scheduling app with an API tacked on.
📖 Try AvailEngine →Here are the specific limitations that make Calendly unsuitable for API-first scheduling workflows — and how AvailEngine fixes each one.
✗ Calendly's API cannot create scheduling events programmatically
Calendly's v2 API only lets you read and list events. To create a booking, a user must go through the Calendly redirect flow, pick a time slot in Calendly's UI, and be redirected back. There is no POST /events endpoint.
✓ AvailEngine: Create events with one curl call
✗ Calendly forces users to leave your product to book
Calendly's core model is: share a Calendly link → user visits Calendly's site → picks a slot → gets redirected. You cannot embed the scheduling flow into your own application without an iframe or redirect. There is no booking widget API.
✓ AvailEngine: Full REST API — build your own booking UI or use the optional dashboard
With AvailEngine, you own the entire booking experience. Your users never leave your app. Use our API to render availability slots, accept bookings, and collect payments — all inside your own interface.
✗ Calendly webhooks only cover basic lifecycle events
Calendly sends webhooks for invitee.created, invitee.canceled, and a few others. There's no webhook for payment events, no granular event filtering, and retry configuration is minimal.
✓ AvailEngine: Full webhook lifecycle with retries and filtering
AvailEngine emits webhooks for every scheduling event: booking.created, booking.confirmed, booking.cancelled, payment.succeeded, payment.failed, and more. Configurable retry with exponential backoff, signing secrets, and event filtering.
✗ Calendly requires a separate payment integration
Calendly integrates with Stripe for simple payment collection, but deposits and partial payments aren't built into the API. You can't programmatically set deposit amounts, refund deposits via the API, or manage payment flows tied to bookings.
✓ AvailEngine: Stripe deposits are a first-class API feature
Set deposit_cents on any event type. AvailEngine handles the Stripe PaymentIntent lifecycle, including automatic deposit capture on confirmation and full refunds on cancellation — all through the API.
✗ Calendly API keys are all-or-nothing
Calendly's Personal Access Tokens give full access to your Calendly account. There's no way to create scoped tokens for specific operations or tenants.
✓ AvailEngine: Scoped API keys with granular permissions
Generate keys with read-only, write, or admin scopes. Restrict keys to specific tenants. Revoke and rotate without downtime. Built for multi-tenant platforms from day one.
Side-by-side: what each platform offers developers.
| Feature | AvailEngine | Calendly |
|---|---|---|
| Programmatic event creation (POST /events) | ✓ | ✗ |
| Scoped API keys | ✓ | ✗ |
| Multi-tenant architecture | ✓ | ✗ |
| Stripe deposits via API | ✓ | ✗ |
| Idempotency-Key support | ✓ | ✗ |
| Custom webhook events | Full control | Basic only |
| Own the booking UI | Yes — full API | Redirect/iframe only |
| Google Calendar sync | Two-way API | Two-way |
| Free tier | €0/mo | Free (limited) |
| Claude Code / Cursor AI ready | ✓ | ✗ |
Choose AvailEngine if you need to create bookings programmatically, embed scheduling into your own product, collect Stripe deposits at booking time, or manage multiple tenants with scoped API keys. Choose Calendly if you just need a standalone scheduling page for your own calendar.
📖 Get Started with AvailEngine →