Custom field formatting for HubSpot Scheduler

Developer Support APIs & Integrations
1

Hello all,

We have set up a scheduling page for our integration with custom questions in the “Form”. When I attempt to create a booking with this payload, I get the error required form field company does not have a corresponding value.

The docs only say “Any information that’s required in your meeting registration must be included in the request body”, but I can’t find an example of how to format the custom fields. Is there an example of how we need to format custom fields?

3

Hey there @CallRail! Happy to help clarify the formatting for custom form fields in your booking payload.

The formFields array expects objects with name and value properties, where name must match the field’s internal identifier. For a field labeled “Company,” that internal name would be company (lowercase, underscores in place of spaces).

Here’s what a properly formatted payload looks like with that field included:

{
  "slug": "menelson",
  "firstName": "Melinda",
  "lastName": "Nelson",
  "email": "menelson@hubspot.com",
  "startTime": 1726059600000,
  "duration": 1800000,
  "guestEmails": [],
  "timezone": "America/New_York",
  "locale": "en-us",
  "likelyAvailableUserIds": [],
  "formFields": [
    {
      "name": "company",
      "value": "Acme Corp"
    }
  ]
}

If you’re unsure of the exact internal name for each field, you can confirm it by calling:

GET /scheduler/2026-03/meetings/meeting-links/book/{slug}

The response includes a formFields array under customParams that lists all configured fields and their internal names, so you can cross-reference and make sure everything lines up.

Let us know if you run into any other snags!

Cassie, Community Manager

5

@Emmytech @chighsmith Thanks to you both! We were able to successfully push the proper information for scheduling.