In one CartCreate request, you can add up to ten different items to the cart. The quantity of each item can be between 1 and 50. That means in one CartCreate request, you could add up to five-hundred items (10 items * 50 quantity).

Items are specified in parameter pairs, as follows:

Item.N.ItemIdType=[Item identifier]
Item.N.Quantity=[Number of Item.N items]

N is a positive integer. The N value associates the ItemId with the quantity of those items that should be added to the cart, for example:

Item.1.OfferListingId=[An OfferListingId]&
Item.1.Quantity=3&
Item.2.OfferListingId=[An OfferListingId]&
Item.2.Quantity=5&

This request adds three number 1 items and five number 2 items to the remote shopping cart. You could interchange lines without affecting the end result, for example:

Item.1.OfferListingId=[An OfferListingId]&
Item.2.OfferListingId=[An OfferListingId]&
Item.1.Quantity=3&
Item.2.Quantity=5&

The values for N do not have to be listed in ascending or descending order, nor do the values of N need to be sequential. You could, for example, use the values, 1, 4, 7 for N. Also, the value of N is not retained between requests. For that reason, it is permissible to use Item.1 in a CartCreate request and then in a CartAdd request, which adds an item to the cart. In these requests, Item.1 can refer to two completely different items.

The value of adding multiple items to the cart in one request is performance. It takes less time to add ten items in one request than it does to add ten items to the cart in ten separate requests.