L'Allegro is the first evidence-based antidepressant chooser for primary care physicians. It is a point-of-care decision support app, designed to facilitate the initiation of drug treatment in order to optimize the management of unipolar major depressive disorder.

Antidepressant rankings were determined based on the most up-to-date comprehensive literature review. Although current evidence does not favor particular antidepressants on the basis of efficacy alone, clinically important differences in drug side effects were considered in the overall ranking and used to match medications with patient symptom clusters. Where evidence was unavailable, expert opinion and usual practice were considered.

The app was reviewed by family medicine residents and attending physicians of the O'Connor Hospital Family Medicine Residency Program, affiliated with Stanford University School of Medicine.