Step 1: Add a booking question
1
Log in to Cal ID
Log in to your Cal ID account.
2
Select your event
Navigate to the Event Types tab in the left sidebar and select the event you want to modify.
3
Open the Advanced tab
Click the Advanced tab in the top navigation bar.
4
Add a question
In the Booking questions section, click + Add a question.
5
Fill out the question details
- Label: The question text (e.g., “Referral Source”).
- Identifier: Take note of this unique ID (e.g.,
referral). You’ll need this exact word to pre-fill the data later.
6
Add the question
Click Add.
Step 2: Hide a booking question
To record a field in your calendar while keeping it invisible to the attendee, hide it:1
Locate your question
Find your newly added question in the list.
2
Set it to Hidden
Click the switch next to the question to set it to Hidden.
3
Lock the value (optional)
To ensure a user cannot change a pre-filled value even if they find the field, click Edit and check the box “Disable input if the URL identifier is prefilled”.
4
Save
Click Save at the top right of the page.
Step 3: Pre-fill the booking question
To automatically fill a field, append a query parameter to your booking URL that matches your question’s Identifier.- The logic: Use a
?for the first parameter and an&for any additional parameters. - The structure:
URL?identifier=value
Example scenario
- Your booking URL:
https://cal.id/username/eventtype - Your identifier:
referral - The value you want to set:
Instagram
https://cal.id/username/eventtype?referral=Instagram
Example with multiple parameters
If your URL already has parameters (like?overlayCalendar=true), use the & symbol to add your pre-fill data: https://cal.id/username/eventtype?overlayCalendar=true&referral=Instagram
URL parameter behavior
Why use this method?
- Data integrity: As long as the question is Hidden, the booker won’t see it on the page, but the information (e.g., “Referral: Instagram”) still appears in your Google/Outlook Calendar and your Cal ID Dashboard once scheduled.
- Seamless personalization: Send custom links to different partners, each with their own name pre-filled, to see exactly who is driving your bookings.
- Clean forms: Keep the visible form short by capturing background data (like Campaign IDs or User IDs) behind the scenes.
Next steps
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