1. A method executing on a server computer comprising: receiving a connection request from a seller application that is customizable by configuration information that includes a hierarchal product category structure for generating a listing for a product for sale, the seller application executing on a client machine; determining that the seller application has not been customized by a current version of the configuration information; transmitting the current version of the configuration information to the seller application, receiving, from the seller application, a product listing request and a configuration confirmation, the configuration confirmation indicating the seller application on the client machine has been configured using the current version of the configuration information to include the hierarchal product category structure; and generating a product listing using the product listing request.