The 2016­-2017 seismic sequence that struck the Central Italy severely damaging different towns, it showed how the marks of our culture can be deleted in an instant. The TECH4DA system (acronym of Technologies for Damage Assessment) was developed both to preserve the photographic memory and support the survey activities after a disaster. TECH4DA is a semi­-automatic system based on a client­-server architecture optimized for the Android and iOS mobile devices. The capability to store location and aspect of the buildings in different time allow to assess their changes due to an earthquake. TeCH4DA can be used by expert involved in damage assessment, although it has been designed for obtaining relevant contribution also from the citizens. The active and widespread participation of the...