 <p>I have been a devoted user of <a href="http://jmeter.apache.org/" rel="nofollow">Apache JMeter</a> for the past decade and it does offer helpful web load testing functionality for free. Here are some pointers that may help determine if JMeter is right for you:</p> <ol> <li>Apache JMeter is a Java application, so it does have upper limits on resources (memory, sockets, threads). These resources can often be increased or consumption optimized (standard JVM args or jmeter.properties file) for better performance under heavy load testing.</li> <li>When capturing scripts using the "HTTP Proxy Server" node, make sure that you have a "User Defined Variables" node created and populated with your name/value pairs for the test. This will trigger a variable substitution in the proxy server. This is invaluable when you want to parameterize the script.</li> <li>As with tree based structures, position determines scope. Make sure that you isolate actions under the proper node or else they will execute for everything at the same scope. </li> <li>For simulated delays, I have had a good run with the "Uniform Random Timer" where you can specify a lower and upper limit.</li> <li>For validation, the "Response Assertion" is helpful for raw strings and regular expressions.</li> <li>For variable extraction, the "Regular Expression Extractor" allows you to extract a value from a page and reference it in a variable for the rest of the test. Node scope appears to be treated as global for these extractors.</li> <li>When watching the test, "Aggregate Graph" is helpful. "View Results Tree" is useful when troubleshooting, but adds extra memory usage to tests and can cause heavy tests to fail. Note that if you save the results on a listener node, you can reload those results in the control at a later time. Also, if you highlight the table in "Aggregate Graph" or "Aggregate Report", you can paste the results into Excel directly. Very helpful for reporting. </li> </ol> <p>Hopefully this gives you an idea of some of the value and gotchas with Apache JMeter. </p>