Methods and systems for enabling access to listing performance data, used in conjunction with a search engine to order search results, are described. Consistent with some embodiments, a listing performance data engine module processes API commands received from client computing systems. The data engine module processes the API commands to identify and communicate relevant listing performance data that is used by a listing performance algorithm to assign a listing performance score to item listings satisfying a search request. The listing performance data provides sellers who have items listed for sale an insight as to how their item listings are performing in comparison to other item listings.