1. A content modification system comprising: a web server to receive a request from a client for a web page and send an optimized web page to the client in response to the request; a treatment controller at the web server and configured to receive a representation of the requested web page from an optimization digital platform and to receive at least one modification instruction for the requested web page from the optimization digital platform, wherein the representation includes controls representing elements of the requested web page and the at least one modification instruction identifies a control in the representation to modify; and a handler at the treatment controller to interface with the representation to identify the control in the representation to be modified and to modify the control in the representation as specified in the at least one modification instruction to generate the optimized web page.