Biologic drugs offer important treatment options for patients suffering from auto-immune disorders such as rheumatoid arthritis and for common cancers including breast and colon. Biosimilar and interchangeable products, which can loosely be thought of as ‘generic’ biologics, are important for promoting competition and driving down costs. The FDA maintains a list of approved biosimilars in the Purple Book. The Biosimilar iOS app provides a handy reference to the Purple Book as well as important information related to prescribing and dispensing for clinicians and pharmacists navigating this complex area of drug therapeutics. ** Disclaimer ** - non-medical users should ask for a doctor’s advice in addition to using this app and before making any medical decisions.