OpenEvidence, founded in 2022 by Daniel Nadler, who previously built and sold Kensho Technologies to S&P Global for roughly $700 million, and Harvard AI researcher Zachary Ziegler, gives physicians point-of-care answers grounded in peer-reviewed medical literature with citations included, rather than a general-purpose chatbot's unsourced responses.
That evidence-grounded design drove what the company calls the fastest-growing physician application in history: OpenEvidence reached 760,000 registered US physicians, about 40% of all US doctors, handling roughly 18 million clinical consultations monthly, and its valuation doubled to $12 billion on a $250 million Series D in January 2026, up from a $3.5 billion valuation less than a year earlier.
OpenEvidence is free for verified physicians and healthcare providers, monetized instead through pharmaceutical advertising and sponsored content shown alongside evidence-based answers. For a physician who wants point-of-care clinical answers grounded in peer-reviewed literature with citations, rather than a general AI chatbot's unsourced response, OpenEvidence's evidence-first design addresses that directly.
