A database search apparatus and method for generating a search result list which responds to Extensible Markup Language (XML) requests from a client to a server of an on-line marketplace. A bid management tool is operable on a client computer to manage search listings and account information of one or more advertisers. The client application communicates with the server via an XML-based application program interface. The bid management tool provides functions for reporting account activity, modifying accounts and manual, timed or event-driven changes to search listings including listings of several advertisers.