Why Prefill #
When you already know who the visitor is, prefilling removes a form step and measurably increases completion. It also keeps campaign attribution attached to the resulting booking.
Standard Parameters #
| Parameter | Fills |
|---|---|
name |
Invitee name field |
email |
Invitee email field |
notes |
Default notes field |
month |
Opens the calendar on a given month, as YYYY-MM |
timezone |
Preselects a time zone, as an IANA name |
Example: https://mixcalendar.mixcommerce.co/priya/discovery-call?name=Anil%[email protected]
Custom Questions #
Prefill a custom question using its slug prefixed with a_, for example ?a_company=Acme%20Ltd. Slugs are shown beside each question in the event type editor. Values must be URL encoded.
Hidden Tracking Fields #
Any parameter beginning with utm_ is captured and stored on the booking without being displayed. These values appear in exports, in the API, and in webhook payloads, which is how bookings are attributed back to a campaign.
Locking Prefilled Values #
Add lock=email to render a prefilled field read-only. Use this when the address must match a record on your side. Locking is a convenience rather than a security control, since anyone can edit a URL, so verify identity server-side if it matters.
Prefill in Embeds #
Both embed modes accept a prefill object in the init call, which is preferable to string concatenation because encoding is handled for you.
