The present invention relates to the field of data processing, and particularly to a software system and associated method for use with a search engine. The engine searches data maintained in systems that are linked together over an associated network such as the Internet. More specifically, this invention pertains to a computer software product for determining, comparing, and representing the similarity between documents using a drag and drop Graphical User Interface (GUI) within a dynamically generated list of document identifiers. The invention uses this drag and drop GUI interface for convenient selection of document identifiers for further comparison. Then processing of a similarity analysis request using a configurable similarity algorithm is executed; this processing can be done on the client, proxy or server side. When the comparison process is completed, the GUI presents the similarity result of the comparison process as a Venn Diagram to show the level of similarity between the selected documents.