A method is performed at a proxy server having one or more processors and memory. The memory stores instructions configured for execution by the one or more processors. The proxy server is coupled to one or more web servers and a user device. The proxy server receives, from the user device, a request for a web page provided by a first web server. The proxy server receives the web page, in response to the request, from the first web server. The web page includes a script. The proxy server scans the script to identify one or more URLs that specify requests directed to servers other than the proxy server. For each of the one or more URLs, the proxy server rewrites the script to redirect requests for the respective URL through the proxy server. The proxy server then sends the web page, including the rewritten script, to the user device.