Daniel Nadler's father spent his working life listening for trouble. He was an engineer who used sound to find microscopic cracks in bridges and submarines, flaws no eye could see until something failed.
His parents had come from Poland and Romania, and Daniel was born in Toronto in 1983. He went to Harvard to study mathematics and classics, and he sat in poetry classes taught by the Pulitzer Prize winner Jorie Graham. It was an unusual double life for a future founder: equations by day, ancient verse after.
He went to Harvard to study mathematics and classics, and he sat in poetry classes taught by the Pulitzer Prize winner Jorie Graham.
In 2013, still a doctoral student, he co-founded Kensho with Peter Kruskall, building machine learning for Wall Street. He was also finishing a Harvard PhD on how credit derivatives are priced, and he spent time as a visiting scholar at the Federal Reserve. In 2016 Farrar, Straus and Giroux published his first poetry collection, Lacunae: 100 Imagined Ancient Love Poems, which the Washington Post called a striking debut.
What the profiles rarely connect is the detail about his father. The sources I could read say nothing about what Nadler felt about it, and I will not invent it. But a man who spent his life finding hidden faults before they became disasters raised a son who sold his first company, in 2018, to S&P Global for $550 million by one account and about $700 million by NBC's.
Then he went looking for another place where something was quietly failing. Doctors, he saw, were drowning in studies they had no time to read. In 2021 he founded OpenEvidence with Zachary Ziegler. A physician asks a clinical question in plain English and gets an answer with citations. It is free to verified doctors and paid for by advertising, and it signed content deals with the AMA, the New England Journal of Medicine and the JAMA Network.
The growth was steep. A $75 million round at $1 billion in February 2025. $3.5 billion by July, when 430,000 US physicians, about 40% of the country's doctors, were registered. $12 billion in January 2026 and a reported $15 billion in September. Forbes put his net worth at $7.6 billion in 2026.
Not everything is settled. In June 2025 the company accused a competitor of hacking its prompts. Revenue is undisclosed, and an advertising-funded tool that advises doctors invites questions about influence.
A founder can take one thing from Nadler: find the person who has the daily pain and the least time, and charge somebody else.