Web caching is the most important technique to reduce network bandwidth consumption and minimize user-perceived latency. However, most researches are focused on designing ef.cient architectures with dedicated proxy servers, the potential advantage of utilizing client cache is not fully exploited. In this paper, we propose a new solution to improve web caching performance using local cache on client computers. Our system has several advantages than the dedicated proxy server mechanism. First, a larger virtual cache is generated to cache more documents than a single proxy server. Second, it is scalable, system workloads are distributed all across client computers instead of concentrated on a central server, the "hot spot" and "single point of failure" problems are relieved. Third, by the introduction of the superclients, the effect of the weak clients in a fully decentralized scheme is also alleviated. The simulation results show our system can achieve better system caching performance and scalability than the previous solutions.