Abstract: One aspect of the invention is generating for a client (a marketer) a measure of relevance of online creative content for online marketing to a set of target users. Another is an interactive user interface for displaying such a measure. Another aspect of the invention is determining a signature of creative content and of components thereof. The measure of relevance is based on profiles of the targeted users and on the signature of the creative content. Another aspect of the invention providing a mechanism to improve the relevance by modifying one or more components of the creative content with respective alternate components, thus suggesting to the client modifications to the content together with a measure of how such modification changes the relevance. Another aspects is providing for an operator the user interface for viewing in real time the effect of such modifications.