How to Hide and Prefill Booking Questions?
In Cal ID, prefill what you already know and hide fields meant only for internal tracking (referral source, Lead IDs) — keeping your form short while capturing useful data.
- Open Event Types and click Edit on the event.
- Open the Advanced tab and, in Booking questions, click + Add a question.
- Set the Label (e.g., "Referral Source") and note the Identifier (e.g.,
referral) — you'll need it exactly to prefill later. Click Add.
To record a field in your calendar but hide it from the guest:
- Toggle the question to Hidden.
- Optionally click Edit and tick "Disable input if the URL identifier is prefilled" so guests can't change a prefilled value.
- Click Save.
Append a query parameter matching the question's Identifier: URL?identifier=value (use ? for the first parameter, & for more).
Example: identifier referral, value Instagram →https://cal.id/username/eventtype?referral=Instagram
If the URL already has parameters, chain with &:https://cal.id/username/eventtype?overlayCalendar=true&referral=Instagram
- Data integrity: a hidden question still records its value (e.g., "Referral: Instagram") in your calendar and dashboard.
- Personalization: send partners their own prefilled links to see who drives bookings.
- Clean forms: capture campaign or user IDs behind the scenes.
Updated on: 04/08/2026
Thank you!