1. A computer system for rewriting initial web content query responses from a web server, the system comprising: a processor and memory configured to execute software instructions; a web content query response receiving component configured to receive an initial web content query response to a web content query, the initial web content query response comprising a web page comprising a plurality of links and a content; a rule definition component configured to allow an administrator to define one or more rewriting rules for rewriting the received initial web content query response; a rule data store configured to store defined rewriting rules to be accessed in response to received web content query responses; a rule indexing component configured to identify defined rewriting rules of the rule data store and determine a union of matching filters defined within the rewriting rules; a web content query response parsing component configured to parse the received initial web content query response and invoke a rule execution component for one or more patterns within the initial web content query response that match one or more matching filters of the defined rewriting rules to produce a rewritten web content query response, wherein the web content query response parsing component is further configured to, upon encountering a pattern of an HTML tag within the initial web content query response, retrieve a rule list from the rule indexing component to determine if the HTML tag within the initial web content query response matches one or more rewriting rules, wherein the response parsing component is further configured to store a first modified output web content query response modified by a first rewriting rule to supply as input to a next rewriting rule in an iterated sequence of rewriting rules; a rule execution component configured to execute one or more rewriting rules on a portion of the web content query response provided by the web content query response parsing component; and a web content query response sending component configured to pass the rewritten web content query response back to a sender from which the initial web content query response was received.