The Content Transform Proxy (CTP) service is an advanced Web proxy service, the basic function of which is to modify incoming HTTP requests having a server-side destination and/or outgoing HTTP responses. The CTP service is implemented by the CTP program, which resides on a host in a data communications network between an end user (the Web client) and a content server that the client is attempting to access. The HTTP request and/or an HTTP response is modified by making an HTTP request on the client side using a client web browser, processing the HTTP request on the server side using outgoing proxy rules, passing on the processed HTTP transaction to the server-side destination, returning the results of the processed HTTP request from the server-side destination, processing the HTTP response on the server side using incoming proxy rules, and returning the processed HTTP response to the client web browser on the client side.