A significant portion of U.S. doctors, estimated at around 65%, are reportedly using a free, ad-supported AI chatbot called OpenEvidence in their clinical practice. This platform, which claims to be "America's Official Medical Knowledge Platform," provides detailed answers with citations and saw rapid user growth, doubling its doctor sign-ups in approximately seven months to reach 50% of American doctors. Despite its free access for healthcare professionals, OpenEvidence is a high-value tech company with a $12 billion valuation, generating revenue through ads, often from pharmaceutical and medical device companies. While doctors primarily consult the sources only for unexpected results, concerns have been raised regarding the tool's occasional inaccuracies, particularly with rare conditions, and its potential to hinder the development of essential diagnostic skills in newer medical practitioners due to a lack of rigorous patient impact studies.