title: Any suggestions for good automated web load testing tool?
body: <p>What are some good automated tools for load testing (stress testing) web applications, that do <strong>not</strong> use record and replay of HTTP network packets?</p>
  
  <p>I am aware that there are numerous load testing tools on the market that record and replay HTTP network packets. But these are unsuitable for my purpose, because of this:</p>
  
  <ul>
  <li><p>The HTTP packet format changes very often in our application (e.g. when
  we optimize an AJAX call). We do not want to adapt all test scripts just because
  there is a slight change in HTTP packet format.</p></li>
  <li><p>Our test team shall not need to know any internals about our application
  to write their test scripts. A tool that replays HTTP packets, however, requires
  the team to know the format of HTTP requests and responses, such that they
  can adapt details of the replayed HTTP packets (e.g. user name).</p></li>
  </ul>
  
  <p>The automated load testing tool I am looking for should be able to let the test team write "black box" test scripts such as:</p>
  
  <ul>
  <li>Invoke web page at URL <em>http://...</em> .</li>
  <li>First, enter <em>XXX</em> into text field <em>XXX</em>.</li>
  <li>Then, press button <em>XXX</em>.</li>
  <li>Wait until response has been received from web server.</li>
  <li>Verify that text field <em>XXX</em> now contains the text <em>XXX</em>.</li>
  </ul>
  
  <p>The tool should be able to simulate up to several 1000 users, and it should be compatible with web applications using ASP.NET and AJAX.</p>