Limitations
The method is available for administrator users only.

Data type header when the request is successful
Content-Type: application/hal+json

Data type header in case of an error
Content-Type: application/problem+json

Request parameters
To add a custom field, a field object should be passed.

Parameter	Data type	Description	Is the field mandatory	Supported field types
type	string	Field type	✅	Available for all field types
name	string	Field name	✅	Available for all field types
code	string	Field code that can be used to update the value of the field without passing the field ID in the request	❌	Available for all field types
sort	int	Field sorting in the field group	❌	Available for all field types
group_id	string	Field group ID	❌	Available for all lead, contact, company fields
is_api_only	bool	Defines whether the field is editable via API only	❌	Available for all lead, contact, and company fields
required_statuses	array\|null	Array of the fields required to change a lead status	❌	Available for all lead, contact, and company fields
required_statuses[0]	object	Required field model	❌	Available for all lead, contact, and company fields
required_statuses[0][status_id]	int	ID of the stage which requires the current field to have a value before the lead can be moved	❌	Available for all lead, contact, and company fields
required_statuses[0][pipeline_id]	int	ID of the pipeline which requires the current field to have a value before the lead can be moved	❌	Available for all lead, contact, and company fields
remind	string\|null	Birthday reminders setting (never, day – day before the event, week – week before the event, month – month before the event)	❌	Available only for the birthday type fields
enums	array	Available field values array	✅	Available for the following field types: -multiselect -radiobutton -select
enums[0]	object	Available field value model	✅	Available for the following field types: -multiselect -radiobutton -select
enums[0][value]	string	Value	✅	Available for the following field types: -multiselect -radiobutton -select
enums[0][sort]	string	Value sorting	✅	Available for the following field types: -multiselect -radiobutton -select