Use this endpoint to retrieve custom field definitions and the options related to each custom field definition by company. Returns Custom Field Definitions for types "contact" and "job" with only active status. Includes field options with active status by default. Custom Field Definitions are returned by grouped by field type . StartIndex starts at 0. Default PageSize is 25. Pagination parameters are optional. You can filter by type 'jobs' or 'contacts'. By default both filters are included. e.g. ?filter=jobs. Valid includes are 'user'. e.g. ?includes=user