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Calendly · architecture

How a booked meeting reaches the ad platforms — Calendly

Calendly's embed runs in an iframe on another origin. The parent page cannot see inside it, which is why so many accounts optimize toward the page that shows the widget rather than toward an actual booking.

1. 1

   Click IDs are captured before the widget loads

   gclid, fbclid, msclkid and li_fat_id are read from the landing URL and written to a first-party cookie, then passed into the Calendly embed as UTM or custom parameters so the booking record carries them.

2. 2

   The embed emits events the parent can listen to

   Calendly's embed posts messages for profile view, date selection and event scheduled. Listening to these gives real funnel steps instead of a single page view.

3. 3

   The webhook is the authoritative booking

   Calendly's invitee.created webhook is the event that means a meeting exists. Anything read from the browser can be lost to a redirect or a closed tab.

4. 4

   Cancellations and no-shows come back too

   invitee.canceled reverses the conversion. Without it, bidding optimizes toward an audience that books and never attends — which is a real and common failure on cheap lead traffic.

5. 5

   A server container joins the booking to the click

   The webhook payload carries the identifiers stored at step one, so the conversion sent to Google, Meta or LinkedIn is attributable rather than anonymous.