  N-of-1 trials are the gold standard study design to evaluate individual
treatment effects and derive personalized treatment strategies. Digital tools
have the potential to initiate a new era of N-of-1 trials in terms of scale and
scope, but fully-functional platforms are not yet available. Here, we present
the open source StudyU platform which includes the StudyU designer and StudyU
app. With the StudyU designer, scientists are given a collaborative web
application to digitally specify, publish, and conduct N-of-1 trials. The
StudyU app is a smartphone application with innovative user-centric elements
for participants to partake in the published trials and assess the effects of
different interventions on their health. Thereby, the StudyU platform allows
clinicians and researchers worldwide to easily design and conduct digital
N-of-1 trials in a safe manner. We envision that StudyU can change the
landscape of personalized treatments both for patients and healthy individuals,
democratize and personalize evidence generation for self-optimization and
medicine, and can be integrated in clinical practice.
