1. A method comprising: in a server comprising one or more processors and a memory system adapted to store one or more computer programs for execution by the one or more processors: receiving, at a taint engine of the server, a request from a web application of a client system via a communications link, the request comprising a request header and a request body; performing a parsing process by a parser of the taint engine of the server, the parsing process including: parsing the request into the request header and the request body and including code associated with the parsed request header and the parsed request body; identifying at least one non-literal token in a syntax of the code, the at least one non-literal token indicative of an attacker-injected code associated with a portion of the code, and upon identifying the at least one non-literal token, executing a portion of the code not associated with the at least one non-literal token while avoiding execution of the portion of the code associated with the at least one non-literal token; generating a standard network transfer protocol response comprising a response header and a response body in response to the request from the client system, the generated standard network transfer protocol response void of the portion of the code associated with the at least one non-literal token; evaluating a request taint value in the request header to determine whether the request is a standard network transfer protocol request or a multipart network transfer protocol request; if the request is a multipart network transfer protocol request, constructing a multipart network transfer protocol response based on the generated standard network transfer protocol response, the multipart network transfer protocol response further comprising: a first subpart comprising a taint version header and taint information, and a second subpart comprising a content type header and the response body of the standard network transfer protocol; and communicating the multipart network transfer protocol response to the client system, wherein the client system is configured to detect tainted content based on the multipart network transfer protocol response.