In this paper, we present VisQI (VISual Query interface Integration system), a Deep Web integration system. VisQI is capable of (1) transforming Web query interfaces into hierarchically structured representations, (2) of classifying them into application domains and (3) of matching the elements of different interfaces. Thus VisQI contains solutions for the major challenges in building Deep Web integration systems. The system comes along with a full-fledged evaluation system that automatically compares generated data structures against a gold standard. VisQI has a framework-like architecture such that other developers can reuse its components easily.