The Checkout API now includes a new Split a cart item endpoint, which splits a single item in a cart into multiple items, distributing its current quantity among them. For example, this allows different shipping or fulfillment rules to be applied to portions of the same SKU.

To split a cart item, send a POST request to the Split a cart item endpoint, specifying the cart's orderFormId and the item's uniqueId as the itemUniqueId path parameter. In the request body, provide an array of objects, each with a quantity value. The endpoint will then split the original item into the same number of new items as objects in the array, assigning each new item the specified quantity and a new uniqueId. The total sum of quantity values in the request must exactly match the current quantity of the item being split.

This request fails if the item's noSplitItem field is set to true. To check or change this configuration, use the Handle cart items request.

No action is required. This is a new, optional endpoint available for merchants and partners who need to programmatically split cart items.