The research pointed out the feasibility of crowd monitoring through WiFi data. A methodology has been developed and tested using real data. The data were collected during the JRC Open Day 2016 by 20 WiFi access points deployed on the Ispra site. The methodology includes a cleaning procedure to identify actual users and a user localization technique based on a modified WeC approach. The estimated number of attending people were compared with the statistics of the security service showing evident consistency; the possibility to validate the results with independent information represents a significant added value to this research. Finally, the proposed approach allowed to reconstruct the distribution of people within the site in different time spots.