Appointment booking API - online booking system API

Fetch open time slots in real time

One GET request - you get open slots for any service, employee, and time zone. Public availability requires no authentication. Build your own booking widget in under a day.

Start integrating View API docs

Get available slots

GET /api/available-slots
    ?service_id=5
    &start_date=2026-04-01
    &number_of_days=7
    &customer_time_zone=Europe/Warsaw

Response 200

{
  "5": {
    "2026-04-01": [
      "09:00", "09:30", "10:00",
      "10:30", "14:00", "15:00"
    ],
    "2026-04-02": [
      "09:00", "09:30"
    ]
  }
}

Create a booking

POST /api/bookings
X-Api-Key: your-api-key
X-Tenant: your-tenant-id

{
  "employee_id": 10,
  "user_id": 200,
  "service_id": 5,
  "start_date": "2026-04-15",
  "start_time": "10:00",
  "status": "approved"
}

Response 201

{
  "id": 5001,
  "employee_id": 10,
  "start_date": "2026-04-15",
  "start_time": "10:00",
  "status": "approved",
  "service": {
    "name": "Consultation",
    "duration": 60,
    "price": 10000
  }
}

Create appointment bookings from any app

Send a POST with employee, service, date, and time. The booking shows up in the calendar right away. Confirmations and reminders? Calendesk sends them for you. One request - one booking.

Start integrating View API docs

Get instant alerts with webhooks

A client books an appointment - your app knows instantly. Payments, cancellations, reschedules - every event delivered straight to your URL. No polling.

Start integrating View API docs

POST /api/admin/webhooks
X-Api-Key: your-api-key
X-Tenant: your-tenant-id

{
  "url": "https://your-app.com/hooks",
  "events": [
    "booking_created",
    "booking_updated",
    "booking_paid"
  ]
}

Response 201

{
  "id": 1,
  "url": "https://your-app.com/hooks",
  "events": [
    "booking_created",
    "booking_updated",
    "booking_paid"
  ]
}

Search customers

GET /api/admin/users
    ?query=[email protected]
    &limit=10
X-Api-Key: your-api-key
X-Tenant: your-tenant-id

Response 200

{
  "current_page": 1,
  "data": [{
    "id": 200,
    "name": "Jane",
    "surname": "Smith",
    "email": "[email protected]",
    "status": "active"
  }],
  "total": 1
}

Search customer records and booking history

Look up any client by email, phone, or name. Full appointment history comes back in one call - with filters, sorting, and pagination built in.

Start integrating View API docs

What's inside the booking API?

Simple 2-header auth

Add your API key and tenant ID to the request headers. That is it. No OAuth dance, no token refresh, nothing to expire.

Pagination on every list

Every endpoint that returns a list supports pages, sorting, and filters. Bookings, customers, services - all work the same way.

Automatic notifications

Every booking triggers email and SMS confirmations automatically. Reminders go out before the appointment. You don't write notification logic - Calendesk handles it.