Abstract: Techniques for replacing an advertisement in a webpage from a website with another advertisement are disclosed. A response including the webpage is intercepted in a network device deployed in an in-line fashion, preferably at a data traffic point along a network. When it is determined that the webpage includes an advertisement that is replaceable, a preferable advertisement more correlated to the interests of a user is embedded in data packets to replace those for the original advertisement. Subsequently, the preferable advertisement is served when the webpage is displayed.