The German app does not use location detection to create movement profiles and uses bluetooth to detect other app users in the vicinity. The app stores all random codes gathered by the phone. According to the Robert Koch Institute, the research institute responsible for disease control and prevention, the incubation period is a maximum of 14 days. Thus, the data is deleted automatically after a fortnight.
If a person reports an infection via the app, their random codes are made available to all other users. The app checks whether that code is among contacts made in the past 14 days and whether any were critical. In that case, it notifies those affected and gives clear recommendations for action. The data of the persons notified cannot be viewed at any time.