The authors analysed app features for the care of patients with rare liver diseases. Mobile health apps enable exhaustive data collection. Therefore, ERN RARE-LIVER intends to implement an app for pa-tients with rare liver diseases communicating with our patient registry. However, little is known about which features patients and their healthcare providers regard as being useful. This study aimed to in-vestigate how an app for rare liver diseases would be accepted, and to find out which features are considered useful by patients and their carers. An anonymous survey was conducted on adult patients with rare liver diseases at a single academic, tertiary care outpatient-service. Additionally, medical experts of the ERN working group on autoimmune hepatitis were invited to participate in an online survey. One of the results was that patients more often expected a simplified healthcare pathway by the app, e.g. by access to one’s own medical record, while healthcare providers saw the benefit mainly in improving compliance and treatment outcome.