Create a custom field

When the field_type is dropdown, radio, checkbox or listbox, you need to add field options using fieldOption/bulk endpoint.
A User can only see a custom field if the contact is part of a list that this custom field is related to. Use fieldRel endpoint to specify which list gets to see the custom field.
📘
This endpoint creates a custom field, but does not populate it with options, if it requires them.
The dropdown, multiselect, radio, and checkbox custom fields need to be supplied with options. To learn more, see our Custom Objets Api Guide

Example `POST` Body

{
	"field": {
		"type": "textarea",
		"title": "Field Title",
		"descript": "Field description",
		"perstag": "Personalized Tag",
		"defval": "Default Value",
		"visible": 1,
		"ordernum": 1
    }
}

{
	"field": {
		"type": "text",
		"title": "Field Title",
		"descript": "Field description",
		"perstag": "Personalized Tag",
		"defval": "Default Value",
		"visible": 1,
		"ordernum": 1
    }
}

{
	"field": {
		"type": "date",
		"title": "Field Title",
		"descript": "Field description",
		"perstag": "Personalized Tag",
		"defval": "2025-01-01",
		"visible": 1,
		"ordernum": 1
    }
}

{
	"field": {
		"type": "dropdown",
		"title": "Field Title",
		"descript": "Field description",
		"perstag": "Personalized Tag",
		"visible": 1,
		"ordernum": 1
    }
}

{
	"field": {
		"type": "listbox",
		"title": "Field Title",
		"descript": "Field description",
		"perstag": "Personalized Tag",
		"visible": 1,
		"ordernum": 1
    }
}

{
	"field": {
		"type": "radio",
		"title": "Field Title",
		"descript": "Field description",
		"perstag": "Personalized Tag",
		"visible": 1,
		"ordernum": 1
    }
}

{
	"field": {
		"type": "checkbox",
		"title": "Field Title",
		"descript": "Field description",
		"perstag": "Personalized Tag",
		"visible": 1,
		"ordernum": 1
    }
}

{
	"field": {
		"type": "hidden",
		"title": "Field Title",
		"descript": "Field description",
		"perstag": "Personalized Tag",
		"defval": "Default Value",
		"visible": 1,
		"ordernum": 1
    }
}

{
	"field": {
		"type": "datetime",
		"title": "Field Title",
		"descript": "Field description",
		"perstag": "Personalized Tag",
		"defval": "2025-05-19T02:45:00-05:00",
		"visible": 1,
		"ordernum": 1
    }
}

{
	"field": {
		"type": "number",
		"title": "Field Title",
		"descript": "Field description",
		"perstag": "Personalized Tag",
		"defval": "1234",
		"visible": 1,
		"ordernum": 1
    }
}

This endpoint creates a custom field, but does not populate it with options, if it requires them.

Example POST Body

Example `POST` Body