JUnitFactory is a free experimental project from AgitarLabs. You send it Java code and it sends back JUnit characterization tests for your code.

We have made our technology freely available to academic institutions and test researchers, but some of them don't have the spare computing or IT resources to set-up a test server, so we thought it would be a fun experiment to set-up a dozen CPUs and have students and researchers use the test generator over the web. As the experiment progresses, we plan to make APIs available so that researchers and anyone interested in automated test generation can experiment with their own characterization test generation algorithms and strategies.