WebTest is a free open source tool for automated testing of web applications
We have been using Canoo WebTest for over a year in our nightly smoke, running it from our main build.xml. It tests our web frontends, both for performance and compliance to standards. As a side effect, it captures each night the then current output of reports in PDF and Excel format and the webpages itself. These captures are used to daily update the manual with current screenshots. In general stable. With long running actions (thousands of web requests) sometimes after one, two or more hours a java.util.ConcurrentModificationException can be thrown from webtest source when calling org.apache.tools.ant.Project.getProperty, so keep your webtest small and/or --keep-going.