In embodiments of the present invention improved capabilities are described for selective website vulnerability and infection testing and intelligently paced rigorous direct website testing. By providing robust website content integrity checking while only lightly loading the website hosting server, visitor bandwidth availability is maintained through selective testing and intelligently paced external website exercising. A modular pod-based computing architecture of interconnected severs configured with a sharded database facilitates selective website testing and intelligent direct website test pacing while providing scalability to support large numbers of website testing subscribers.