We demonstrate a system to automatically grab data from data intensive web sites. The system first infers a model that describes at the intensional level the web site as a collection of classes; each class represents a set of structurally homogeneous pages, and it is associated with a small set of representative pages. Based on the model a library of wrappers, one per class, is then inferred, with the help an external wrapper generator. The model, together with the library of wrappers, can thus be used to navigate the site and extract the data.