Products massive add has been created to make your business life easier.
Now you can select all products listed on your page (even if are the result of multiple filters selection) and add them all together with just two clicks. [Pro & Business profiles]
At the same time you can choose to import the whole category by clicking "Select all xxxx products" below the Select all checkbox. [only Business profiles]

These two features are resources consuming for ApiDrop, that's why we released them for our PRO and BUSINESS users.
The "Select all" feature, in fact, is available only for customers who have an ApiDrop PRO subscription while the "Select all xxxx products" (which adds the whole category products) is available only to Business users.
The adding procedure is synchronous so you can expect to wait from some seconds to some minutes, depending on how many products you are adding.