DOUBLE TAP AND DONE

A computer-implemented method for using a mobile computing device corresponding to a user to purchase a product being offered for sale by a user includes, when the mobile computing device has selected an item indicating the product, obtaining item information related to the item. Item display data is generated based on the item information and transmitted to the mobile computing device. The item display data prompts the mobile computing device to display the item information and an operational input in a graphical user interface of the mobile computing device. A command is received in response to a prescribed number of actions input by the user to the operational input. The command causes a purchasing server to perform one or more operations.