In networks with heavy WWW traffic, the disk I O performance can become a bottleneck for caching proxies. To solve this problem, we propose a memory-based architecture for WWW caching proxies. The features of the proposed architecture are (1) a cache contents control that retrieves only frequently accessed WWW pages, and (2) an automatic distribution mechanism that enables efficient cache space sharing among multiple caching proxies. A statistical analysis shows that our approach reduces the required cache space. It consumes only 1 10 the cache space of current typical proxies while retaining the same cache hit rate. The reduced cache space enables the use of fast DRAMs in the caching proxies, and solves the disk I O problem.