A Case Study on the Development of the German Corona-Warn-App

The COVID-19 pandemic has drastically changed daily life and required fast responses to new situations, such as restricted public life. A major means to limit infections have been contact-tracing apps that inform an individual about a potential infection, helping to initiate countermeasures faster. While different tracing apps have been compared technologically, we are not aware of studies providing insights into their development processes during the pandemic emergency situation. To address this gap, we report an exploratory case study on how the German open-source Corona-Warn-App has been developed at SAP SE—and how other organizations (e.g., Deutsche Telekom AG), researchers, and individual developers contributed. We elicited data on the process, practices, and challenges by interviewing six developers at SAP SE, analyzing documentation, and discussing our data with an expert on the app’s development. Overall, we provide insights into how the development process of the Corona-Warn-App differed from other projects at SAP SE (e.g., testing), discuss the causes (i.e., public interest causing researchers to perform tests), and study the consequences (i.e., emergency tickets by researchers). Our findings can guide organizations when developing software in similar emergency situations (e.g., pandemics) in which reliable software needs to be developed within a short period of time.