curl --request GET \
  --url https://services.leadconnectorhq.com/locations/{locationId}/customFields \
  --header 'Authorization: Bearer <token>' \
  --header 'Version: <version>'

{
  "customFields": [
    {
      "id": "3sv6UEo51C9Bmpo1cKTq",
      "name": "pincode",
      "fieldKey": "contact.pincode",
      "placeholder": "Pin code",
      "dataType": "TEXT",
      "position": 0,
      "picklistOptions": [
        "first option"
      ],
      "picklistImageOptions": [],
      "isAllowedCustomOption": false,
      "isMultiFileAllowed": true,
      "maxFileLimit": 4,
      "locationId": "3sv6UEo51C9Bmpo1cKTq",
      "model": "opportunity"
    }
  ]
}