Crowded Zone is a Web application that can be reached at
It allows one to know how many people are located in a given place at real-time, and how many people have been there in the past. This way, people come to have one more tool for distributing in space and time, so realizing the so-called “social distancing”, the key weapon against COVID-19. The application also supports the delivery of notifications to users about the possibility of having had a contact with an infected person, in the case in which a public authority would fill in the numeric identifiers of infected people. The basic principle of the application is very simple: users indicate themselves where they locate, so no use is made of GPS or other short distance communication technologies. Shortcuts are available for speeding up the process. Each user is identified through a numeric code that is assigned the first time that the user indicates her position, and it is not linked to any personal information, nor can it be linked indirectly. Abandoned markers stop to be considered after one day. The history of movements is not stored. Instead, when the user communicates a new position, two rows are added to a dedicated table to store the new presences in the origin and in the destination places, simply increasing or decreasing the presences by one. This way, the history of presences is preserved, but the behavior of the single user is not tracked. Also, the user is associated with all bystanders for fourteen days, so that if one of them is filled in as infected in that period, all contacts can be notified through a message on the main map. The interface is also very simple: it is made up of two geographical maps, the main one is for displaying real-time presences and communicating the user’s own position, while the trend one is for browsing among places and displaying the evolution of presences over the time. An Android app is also provided that just opens the browser and loads the main map. The application is open source, and it is very easy to reproduce it at any scale. For a complete introduction and all references and contacts, a FAQ page is available as a part of the Website.


Crowded Zone – a Web App for social-distancing