Abstract: A method of protecting a web server by applying a trusted web engine (TWE) to execute a webpage code in parallel to a client side web engine (CSWE), comprising a proxy server adapt to use a TWE to execute a code of a webpage provided by a web server, issue to the web server a plurality of trusted requests originating from the TWE, receive a plurality of client side requests originating from a CSWE executing the code of the webpage on a client device in parallel to the TWE, receive from the web server a plurality of responses to the plurality of trusted requests and sending to the CSWE at least some of the plurality of responses synchronized by correlating at least some of the plurality of client side requests with corresponding trusted requests according to identification information injected into the at least some client side requests.