Apps are a part of the everyday lives of many people around the world. Digital applications support many areas, including the private sphere and the working world. To strengthen social sustainability in app development, it is necessary to consider users’ needs. The aim of this paper is to identify users’ requirements and to explore possible concerns. Furthermore, we aim to investigate how sustainability can be integrated into app development. For this purpose, 25 studies were analyzed, in which users were interviewed. The papers were qualitatively evaluated. Our results reveal three main findings. First, specific requirements, such as value for monetary aspects, security, and privacy, play a crucial role for users. Second, users expressed concerns about the attractiveness, motivation, and accuracy of apps. Third, an absolute research gap was revealed in the integration of sustainability in app development. Based on the findings, the Sustainable App Development Model (SADM) was then developed. This model incorporates the most fundamental aspects of social, economic, and environmental sustainability and is characterized by a circular approach to app development.