Zebra Tester is a professional web load and stress testing tool which allows you to run performance tests by simulating thousands of virtual users against. It is available as an on-premise and an in-the-cloud (Amazon AWS) offering. With Zebra Tester users can create and run load tests almost unlimited in scale with complete visibility into results.
Proxy Sniffer runs on a virtually unlimited number of operating system and is also available as a cloud-based offering. This should accommodate most requirements in terms of infrastructure allowing you to use a combination of already available hardware and cloud-based virtual machines. The reporting subsystem allows you to clearly understand the results of your load tests and gives you the opportunity to add inline notices before producing the final report. The product can be extended with custom plugins written in Java, a very common programming language.