Exploring user experiences of Kalmer: a focus group of an ecological momentary intervention app for non-suicidal self-injury

Objective Non-suicidal self-injury (NSSI) is a major global public health concern, especially among young people, with emotional, interpersonal, and functional consequences, and an increased risk of later mental disorders and suicidal behaviour. Mobile applications based on Ecological Momentary Assessments (EMA) and Ecological Momentary Interventions (EMI) offer opportunities to deliver real-time support in daily life. This study examined Kalmer, a newly developed mobile app for NSSI intervention.Method Two online focus groups were conducted with nine participants, aged 18–28, who used Kalmer for two weeks. We explored their experiences with mobile app-based interventions and with Kalmer specifically. Data were analysed using grounded theory.Results Three main themes were identified: (1) engagement, involving participants’ motivation, adherence, and therapeutic value of EMA and EMI; (2) use context, highlighting facilitators and barriers of app use; and (3) app design, encompassing usability, accessibility, personalization, and reactions to content generated by artificial intelligence (AI). Participants valued Kalmer as a complementary tool and positively assessed its overall design, while emphasising the need for greater personalization and integration with professional or peer support.Conclusions Findings provide user-driven insights to improve Kalmer and inform the development of digital interventions for NSSI, supporting their clinical applicability and relevance.