Kalmer, a specific based-App intervention for the treatment of Non-suicidal self-injury (NSSI): a technical and usability study in a non-clinical population

Introduction Non-suicidal self-injury (NSSI), defined as the deliberate infliction of harm to oneself without suicidal intent, poses a significant and growing mental health concern worldwide, particularly among adolescents and young adults. This behavior is associated with considerable emotional, social, and economic burdens, and is closely linked to heightened risks of future psychological challenges, including suicidal behavior. Digital interventions based on Ecological Momentary Assessment (EMA) and Ecological Momentary Intervention (EMI) offer promising solutions by overcoming access barriers of traditional therapies. This study introduces Kalmer, a mobile app designed to aid young individuals (ages 14–25) engaging in NSSI, integrating Cognitive Behavioral Therapy (CBT) and Dialectical Behavior Therapy (DBT) strategies. Methods A usability study was conducted with 26 non-clinical participants aged 16–25, evaluating app's functionality, satisfaction, and acceptability. Results Results indicate high usability scores (SUS mean: 81) and positive perceptions regarding quality. Users assess the objective quality to be good (mean = 3.88/5), subjective quality to be improvable (mean = 2,99/5) and perceived the app as useful (mean = 3,66/5). Discussion Kalmer demonstrated potential to increase self-awareness, knowledge, and help-seeking attitudes. Areas for improvement include enhanced content personalization and user engagement. These findings support the feasibility of Kalmer as a complementary tool in NSSI treatment and lay groundwork for future clinical trials in public health contexts.