Participant Custom Fields

Custom fields are additional registration form fields configured in the back-office for each event. They can be set and updated via the API by passing the field's system name as the parameter key in your request.

How to find the field system name

Custom field system names are configured in the back-office under the registration form builder. The system name is the identifier you pass as the parameter key in your API request — it is not the display label visible to participants.

General rules

Pass the field's system name as the parameter key and the value as the parameter value
For multi-value fields (Checkbox Group), separate values with || (double pipe)
Field names must not exceed 64 characters
Custom fields are set via POST /api/v2/account/set — the same endpoint used for all other participant operations
Include only the custom fields you want to change — any field not included will remain unchanged

Note: The custom field types and parameter formats documented below apply identically to exhibitor custom fields via POST /api/v2/exhibitor/set. See the Exhibitors → POST exhibitor/set → Exhibitor Custom Fields section for exhibitor-specific examples.

Field types

Each child page below documents the exact request format for a specific custom field type: