With the default Bookly PRO, your clients have to fill in the minimum details before they confirm the booking. These are the name, phone number, email address, and appointment notes. With the Bookly Custom Fields (Add-on), you can add extra fields of different types on the Details step of your Bookly online booking form. This will allow your customers to add additional information during the booking process. The information entered in the custom fields will be added to the appointment details in your Bookly Calendar, and can be updated if necessary.