Introducing the GESIS AppKit: An app-based mobile data collection infrastructure

This article introduces the GESIS AppKit, an app-based data collection infrastructure and research software. Modern social science research increasingly recognizes the potential of smartphones as both a subject of study and a research tool. The GESIS AppKit addresses critical gaps in mobile research infrastructure by providing an institutionally maintained platform that enables researchers to conduct intensive longitudinal studies such as the Experience Sampling Method (ESM) and Ecological Momentary Assessment (EMA) without requiring programming expertise. The platform facilitates flexible study design through an intuitive web-based interface and delivers questionnaires to participants via a cross-platform mobile application for iOS and Android. A validation study during the 2024 European Parliament election campaign with 678 participants demonstrates the platform's effectiveness, achieving participation and compliance rates consistent with previous research. Released as open-source software and hosted as a free service for academic researchers, the GESIS AppKit removes technical barriers to mobile research and supports methodological advancement in social science research.