OpenEvidence is an AI-powered medical search engine built exclusively for verified physicians. Doctors ask clinical questions — drug interactions, dosing, treatment guidelines, differential diagnoses — and get cited, evidence-grounded answers drawn from peer-reviewed journals and medical literature, not the open internet. The product is free to any NPI-verified clinician; the company makes money by serving highly targeted pharmaceutical and medical device ads during the brief moment while answers load, commanding CPMs of $70–$1,000+ versus $5–15 on typical consumer platforms. Founded in 2022 by Daniel Nadler (previously built Kensho, sold to S&P Global for $700M) and Harvard AI PhD Zachary Ziegler, OpenEvidence spread almost entirely by word-of-mouth. It has since expanded beyond search to include ambient clinical documentation ("Visits"), an AI-integrated HIPAA-secure Doctor Dialer, and EHR integrations (live inside Epic at Sutter Health). The company operates out of Miami and San Francisco with a deliberately small 30-person engineering team.