Web Polygraph is a freely available benchmarking tool for caching proxies, origin server accelerators, L4/7 switches, content filters, and other Web intermediaries. Polygraph's features include:

 *high-performance HTTP clients and servers
 *realistic HTTP and SSL traffic generation
 *flexible content simulation
 *ready-to-use standard workloads
 *powerful domain-specific configuration language
 *portable open-source implementation

Vendor Site:- Web Polygraph