We present HePToX, a full-fledged peer-topeer database system that efficiently handles XML data heterogeneity. In a highly dynamic P2P network, it is unrealistic for a peer entering the network to be forced to agree on a global mediated schema, or to perform heavyweight operations for mapping its schema to neighboring schemas. In our demo, we show that to enter the HePToX network a peer user is only asked to draw a simple set of visual annotations to a few other schemas. We show how the mapping rules are then automatically generated and how efficient query translation is performed on top of these mappings.