ON-PAGE MANIPULATION AND REAL-TIME REPLACEMENT OF CONTENT

A request to render a control content is intercepted by a client application as it is being served from a content source. Based on predetermined criteria, the control content is replaced with replacement content. The replacement content may be an alternative version of the control content differing from the control content in one or more alternative elements. The replacement content may be created with a graphical interface that overlays the control content. The graphical interface allows a user to select elements of the control content, edit the selected elements of the control content, and save the edited elements as part of the replacement content.