HaMagen is a digital tool for fighting the spread of the novel coronavirus. The app can cross-reference information about the location of a confirmed COVID-19 patient with the location of the app user. The app is able to predict whether the user might have been exposed to a confirmed COVID-19 patient with a high degree of accuracy. Upon detection of such an event, the user will receive a notification (including time and location), thus minimizing the likelihood of infection. HaMagen is based on the open-source values of mutual responsibility and can be downloaded free of charge on the App Store and Google Play in five languages: Hebrew, Arabic, English, Russian, and Amharic. The app was launched by the Israeli Ministry of Health.