Described is a technology in which test case content in the form of a web application is provided to a client browser from a test case management system over a web server. Results of running the test case are similarly communicated back. This allows different web application test harnesses to be run on whatever Internet browser the client computing device is running, and is independent of any operating system. The client registers with the test case management system through the website, and receives a browser identifier for use in future communications. In one protocol, the client uses the identifier in heartbeats sent to the test case management system, including a heartbeat indicating when the client is available to run a test case, when the test case is complete, and the results of performing the test case. Also described are various interfaces that facilitate component communication.