Tools for Ajax load testing

Question

There seems to be a lot of stress/load testing tool that support AJAX.
I am wondering how well does these tool implemented.

Do they only record http request and repl

Answer 1

If you don't want to setup your own load testing server there are a couple of free online load testing services that can run load tests directly over the Internet. For example http://loadimpact.com or http://loadstorm.com