What happens when a Harvard mathematician who sold his last company for half a billion builds a machine to outthink your doctor? You get OpenEvidence, the AI engine that just locked in a $210 million Series B and is putting the “clinical” in clinically obsessed with scale.
This round was co-led by Google Ventures and Kleiner Perkins, with Sequoia Capital returning from the Series A like Jordan back in ’95. Coatue, Conviction, Thrive, and Greycroft rounded out the syndicate, and if you’re counting dollars and decimal points, OpenEvidence is now sitting pretty at a $3.5 billion valuation.
Daniel Nadler (Founder & CEO) isn’t new to the game. He built Kensho, sold it to S&P Global for $550 million, and casually picked up a TIME100 Health nod in 2025. His co-founder, Zachary Ziegler (Co-founder & CTO), is a PhD candidate out of Harvard with a résumé that reads like a particle accelerator, Cornell, Goldwater Scholar, NLP research under Alexander Rush. Together, they didn’t just launch a company, they lit a fire under an industry drowning in its own data.
OpenEvidence was born inside the Mayo Clinic Platform Accelerate program with one mission: reduce the signal-to-noise ratio in medicine. In a world where medical literature doubles every five years, their platform pulls 35 million peer-reviewed studies into real-time, evidence-based answers. And not just Google-style links, actual synthesized insights, vetted, visualized, and HIPAA-tight.
And the market noticed. From 358,000 monthly consultations to over 8.5 million in just 12 months. More than 430,000 verified U.S. physicians on board. 65,000 new signups a month. Over 100 million Americans will be treated this year by a doctor who used OpenEvidence. They’re not knocking on the door of healthcare, they’ve already set up shop in 10,000 hospitals and 150 countries.
The launch of DeepConsult, an AI agent that acts like a tireless PhD and thinks like a board-certified doc, is OpenEvidence playing offense, not just triage. It runs on 100x the compute of a typical search but is given away for free to U.S. clinicians. That’s not charity. That’s how you take ground in a land grab.
This round isn’t just a funding story, it’s a case study in building deep tech that physicians actually want to use. Partnerships with NEJM and JAMA? Check. Accuracy that beats ChatGPT, GPT-4, and Med-PaLM 2? Triple check. An elite AI team from Harvard and MIT, housed inside a business with Google-grade security and a DTC growth model? That’s how you go from idea to ubiquity in under three years.
This isn’t just the most widely used medical search engine in the U.S., it’s the new operating system for clinical thinking.
