The world of medical artificial intelligence (AI) has a new headline-making success story: OpenEvidence, a startup rapidly gaining traction as an indispensable clinical tool for physicians. In a major funding round announced in January 2026, the company secured $250 million in Series D financing, propelling its valuation to $12 billion — a meteoric rise that has also doubled the personal wealth of co-founder and CEO Daniel Nadler.
In this comprehensive article, we explore how OpenEvidence achieved this milestone, the technology behind it, its real-world adoption by clinicians, the broader implications for healthcare AI, and what this means for Nadler’s personal fortune and the future of data-driven medicine.
What Is OpenEvidence? The “ChatGPT for Doctors”
OpenEvidence is an AI-powered medical search and clinical decision support platform designed specifically for healthcare professionals — physicians, nurse practitioners, and other clinicians. Its primary purpose is to help users quickly find, aggregate, and interpret evidence from peer-reviewed medical literature, clinical practice guidelines, and trusted scientific sources, all in a fraction of the time it would take to navigate conventional databases.
Unlike general-purpose AI tools such as consumer versions of ChatGPT, OpenEvidence’s models are specialized and trained exclusively on high-quality, medically vetted sources like The New England Journal of Medicine and the Journal of the American Medical Association. This domain-specific focus aims to deliver highly accurate, evidence-based results that clinicians can rely on at the point of care.
Overall, the platform functions much like a clinical research assistant—surfacing relevant studies, summarizing findings, and supporting diagnostic and treatment decisions—which is why many in the industry call it the “ChatGPT for doctors.”
The Journey to $12 Billion: Funding Rounds and Growth
OpenEvidence’s valuation journey has been astonishingly rapid:
Founding and Early Growth (2022–2024)
The startup was co-founded in 2022 by Daniel Nadler and Zachary Ziegler with the mission of organizing and making global medical knowledge instantly accessible to clinicians. Nadler, who holds a Ph.D. and previously founded and sold an AI analytics company, invested early capital from his own pocket into the venture, securing a significant ownership stake.
Series A: $1 Billion Valuation
In early 2025, OpenEvidence raised approximately $75 million in a Series A round led by Sequoia Capital, which valued the company at $1 billion. This early validation underscored investor confidence in the startup’s vision.
Series B and C: Rapid Expansion
By July 2025, the company had raised $210 million in Series B funding at a $3.5 billion valuation, led by Google Ventures and Kleiner Perkins, among others. The Series B round highlighted OpenEvidence’s rapidly growing user base and clinical relevance.
Just three months later, in October 2025, it secured another $200 million at a $6 billion valuation, confirming the startup’s accelerating trajectory in a crowded AI landscape.
Series D: Catapult to $12 Billion
In January 2026, the big breakthrough arrived: a $250 million Series D round co-led by Thrive Capital and DST Global, which doubled the company’s valuation to $12 billion. With this latest capital injection, OpenEvidence’s total funding now approaches $700 million, a testament to sustained investor faith.
Founder’s Wealth Skyrockets: Daniel Nadler’s Rise
The valuation jump hasn’t just been a milestone for the company — it’s been transformational for Daniel Nadler’s personal wealth.
According to Forbes, Nadler’s net worth is now estimated at approximately $7.6 billion, more than twice what it was late last year. That dramatic increase is primarily due to his majority ownership stake in OpenEvidence, which he has retained through multiple funding rounds.
Nadler’s journey to billionaire status isn’t his first rodeo: he previously founded an AI analytics startup that sold for $550 million in 2018, laying the financial groundwork that helped him back OpenEvidence in its earliest days.
His co-founder, Zachary Ziegler, also benefits substantially, with his equity stake now valued at hundreds of millions of dollars.
Real-World Use: Adoption Across U.S. Healthcare
What makes OpenEvidence’s rise particularly compelling is its tangible adoption among clinicians.
By late 2025, the platform was being used by more than 40 % of physicians in the United States, covering over 10,000 hospitals and medical centers nationwide.
Doctors have turned to OpenEvidence in increasing numbers — with the company reporting that its tools supported roughly 18 million clinical consultations in December 2025 alone, a dramatic increase from around 3 million per month a year earlier.
This adoption surge reflects clinicians’ hunger for tools that help them parse the ever-expanding medical literature, which grows at an exponential rate as new treatments, drugs, and studies emerge daily.
Business Model: Free for Physicians, Ads for Revenue
Unlike many startups that charge subscription fees, OpenEvidence’s core platform remains free for verified physicians. Instead, the company generates revenue through advertising — particularly from pharmaceutical and medical device companies seeking to reach clinicians.
According to Nadler, OpenEvidence crossed an annualized revenue run rate exceeding $100 million in 2025, even though most of its paid ad inventory remains unused. He estimates that fully monetized advertising could one day contribute up to a billion dollars in annual revenue, though he prefers to prioritize user experience over aggressive monetization.
This approach is reminiscent of early strategies used by tech giants like Google — prioritizing widespread adoption before maximizing profit — and suggests a long-term growth mindset.
The Technology Behind OpenEvidence
At its core, OpenEvidence leverages specialized large language models (LLMs) trained on medical literature and structured clinical data. Its search algorithms go beyond simple keyword matching; they are designed to understand clinical context, prioritize high-quality evidence, and surface the most relevant information for a given query.
According to external profiles of the company, in 2023 its AI achieved a 90 percent score on the United States Medical Licensing Examination (USMLE) — a testament to its domain-specific accuracy — and later reached 100 percent in subsequent benchmarks. This performance has helped build trust among clinicians who rely on fast, evidence-backed answers during patient care.
Additionally, the platform has introduced features like DeepConsult™, an AI agent purpose-built for physicians that can synthesise findings across multiple studies — further cementing its utility as a clinical decision support tool.
Industry Impact: AI Transforming Clinical Workflows
OpenEvidence’s success mirrors a broader shift in healthcare: the integration of AI tools into clinical workflows to reduce burnout, improve diagnostic accuracy, and shorten research time.
Physicians face an overwhelming volume of new research — published studies are now released faster than ever, making it nearly impossible for any doctor to stay fully updated across all areas of medicine. AI tools like OpenEvidence help bridge that gap by providing real-time access to vetted evidence, reducing the hours clinicians spend combing through journals and databases.
The startup’s rapid adoption suggests that clinicians are not just curious about AI — they are integrating it into everyday care. The platform’s usage across millions of consultations each month shows that AI is increasingly becoming a trusted part of the clinical decision-making process.
Challenges and Competition
Despite its impressive growth, OpenEvidence operates in a competitive and rapidly evolving landscape. Other AI giants, including OpenAI and Anthropic, have launched health-related tools, and the broader market for clinical AI continues to attract investment and innovation.
That said, OpenEvidence’s specialization in medical literature and clinical use cases gives it a defensible position, particularly against general-purpose AI platforms. Its focus on trusted sources and partnerships with leading medical journals further reinforces its credibility among healthcare professionals.
What Comes Next for OpenEvidence
With $700 million in total funding and a $12 billion valuation, OpenEvidence is poised for further expansion. The company says it will use the new capital to invest in research and development, scale its AI infrastructure, and continue enhancing the platform’s capabilities for clinicians worldwide.
Possible future directions include:
- Global expansion into international healthcare markets
- Enhanced clinical decision support tools integrated with electronic health records (EHRs)
- New AI features for drug discovery, patient risk stratification, and personalized care
- Expanded partnerships with healthcare institutions and medical societies
As healthcare continues to embrace digital transformation, OpenEvidence’s model — combining deep clinical focus with advanced AI — may serve as a blueprint for other startups looking to make meaningful impact in the sector.
A Defining Moment for Healthcare AI
OpenEvidence’s rapid ascent from a $1 billion valuation in early 2025 to $12 billion in early 2026 is more than a funding milestone — it signals a broader trend in healthcare innovation. Specialized AI tools that address real clinical needs are now commanding significant investor attention and adoption among frontline clinicians.
For Daniel Nadler, the journey has been transformative, turning his vision into a multi-billion-dollar reality and doubling his personal wealth in the process. But for the healthcare industry as a whole, the real story is how AI is reshaping the way medicine is practiced and how evidence is accessed and applied in real time.
As OpenEvidence continues to grow, the question isn’t just about valuation — it’s about how deeply AI will integrate into clinical workflows and how it will ultimately improve patient outcomes in a world where data is both abundant and indispensable.
