This project aims to compare the effectiveness of Wellnuts, an evidence-based, algorithm-driven self-health assessment mobile application, in empowering asymptomatic young-to-midlife adults in Hong Kong, promoting health awareness, and improving health-seeking behaviour and linkage-to-care, compared with conventional web-based health resources. Participants will be randomly allocated to the mobile health intervention group (Wellnuts app with self-health assessment and health information) and the conventional web-based resources control group (health information from Centre for Health Protection website). Hopefully, population health will be improved with the general health promotion impact from the app.