# Intro Call with Zack Babtkis

> A short call to figure out whether your project and my experience fit. Tell me what you're building and what's in the way; I'll tell you what I'd do about it and I'll also tell you if I'm not the person you're looking for. If we're a fit, most engagements start with a fixed-price assessment, so you'll leave knowing the next step and what it costs.

- Host: Zack Babtkis
- Duration: 20 min
- Location: Google Meet
- Host time zone: America/Los_Angeles
- Confirmation: Bookings are confirmed instantly.
- Booking page: https://cal.com/zack-babtkis/intro-call
- Event type id: 6450427

## Check availability

```http
GET https://api.cal.com/v2/slots?eventTypeId=6450427&start=YYYY-MM-DD&end=YYYY-MM-DD&timeZone=<IANA time zone>
cal-api-version: 2024-09-04
```

The response is `{"data":{"YYYY-MM-DD":[{"start":"<ISO 8601 with offset>"}]}}`; no API key is needed.

## Book

```http
POST https://api.cal.com/v2/bookings
cal-api-version: 2026-02-25
Content-Type: application/json

{
  "eventTypeId": 6450427,
  "start": "<UTC ISO 8601 start from the slots response>",
  "attendee": {
    "name": "…",
    "email": "…",
    "timeZone": "<IANA time zone>"
  },
  "guests": [
    "guest@example.com"
  ],
  "bookingFieldsResponses": {
    "challenge": "…"
  }
}
```

- Required fields: `name` (Your name), `email` (Email address), `challenge` (What    are you building, and what's in the way?)
- Optional fields: `guests` (Add guests)
- `name` and `email` go in `attendee` and `guests` is a list of emails; every other field goes in `bookingFieldsResponses` under its name.