In order to pass form submissions from an external, non-HubSpot form into HubSpot using the forms API, you will need to pass the internal value associated with each contact property option.
So if you are trying to pass a value for HubSpot Owner, you must use the ID number string that you’d see if you viewed the property options for the Contact owner property.
To find these internal values in HubSpot:
- In your HubSpot account, click the settings icon settings in the main navigation bar.
- In the left sidebar menu, click Properties.
- Under the Contacts tab, search for and select the Contact owner property.
- Scroll to the Dropdown options section to see the internal values for each property option.