A web-based customer lead harvesting system. The system is based on an application service model, with the programming for the system being accessible to users of the system via web browsers and the Internet. The users, who are typically business enterprises, may access the system to search unstructured Internet data to obtain leads for prospective customers. The system accepts criteria from the user that describes a type or types of potential customers, as well as addresses of Internet sites of interest. A crawler process retrieves the web site data, and stores the data in a web archive. A harvester process then searches the Internet data according to the client-provided criteria. The system returns the names or the identifying information about the prospect together with a link to the document that verifies the prospect's match to the criteria.