AUTHOR=van 't Klooster Jan-Willem J. R. , Rabago Mayer Lucia M. , Klaassen Bart , Kelders Saskia M. TITLE=Challenges and opportunities in mobile e-coaching JOURNAL=Frontiers in Digital Health VOLUME=Volume 5 - 2023 YEAR=2024 URL=https://www.frontiersin.org/journals/digital-health/articles/10.3389/fdgth.2023.1304089 DOI=10.3389/fdgth.2023.1304089 ISSN=2673-253X ABSTRACT=Background Mobile e-health technologies have proven to provide tailored assessment, intervention and coaching capabilities for a range of usage scenarios. Thanks to their spread and adoption, smartphones are one of the most important carriers for such applications. Problem However, the process of design, realisation, evaluation and implementation of these ehealth solutions is wicked and challenging, requiring multiple stakeholders and expertise. Method Here, we present a tailorable intervention and interaction e-health solution, that allows rapid prototyping, development and evaluation of e-health interventions at scale. This platform allows researchers and clinicians to develop ecological momentary assessment (EMA), just-in-time adaptive interventions (JITAI), ecological momentary intervention (EMI), cohort studies, e-coaching and personalised interventions quickly, with no-code, and in a scalable way. Result The Twente Intervention and Interaction Instrument (TIIM) has been used by over 320 researchers in the last decade. We present the ecosystem and synthesize main scientific output from clinical and research studies in different fields.The importance of mobile e-coaching for prediction, management and prevention of adverse health outcomes is increasing. A profound e-health development strategy, as well as strategic, technical and operational investments are needed to prototype, develop, implement and evaluate e-health solutions. TIIM ecosystem has proven to support these processes. This paper ends with main research opportunities in mobile coaching, including intervention mechanisms, fine-grained monitoring and inclusion of objective biomarker data.