OpenEvidence
Unicorn Β· $12B27 known investors
AI company developing a medical search engine used by physicians for clinical decision support.
Also known as "ChatGPT for doctors" Β· OpenEvidence, Inc.
Founders & leadership

Investors Β· 27
Also in the syndicate Β· 5
Valuation Β· disclosed
Disclosed eventsSource: SEC prospectus filings, and round valuations the company or its investors disclosed β follow each entry's link for the claim.
Company profile
researched Aug 2026OpenEvidence is an American artificial intelligence company that develops a medical search engine and generative AI assistant for healthcare professionals, providing point-of-care clinical decision support. The product lets clinicians enter clinical questions or patient case details and returns synthesized answers grounded in peer-reviewed medical literature, with citations and follow-up suggestions. The platform is HIPAA compliant and is free to U.S.-based clinicians, who must verify their National Provider Identifier (NPI) number through the NPPES registry to register.
The platform's answers are grounded in licensed content rather than the open internet. OpenEvidence describes itself as an official AI partner of The New England Journal of Medicine, JAMA and the JAMA Network specialty journals, Nature and the Nature Portfolio, and Cochrane Systematic Reviews, and as having an official AI collaboration with the National Comprehensive Cancer Network covering NCCN Guidelines treatment algorithms. Other content and organizational partners cited include the American Medical Association, the American Academy of Family Physicians and the American College of Emergency Physicians.
Beyond search, the product line has expanded into agentic and workflow features, including DeepConsult (an AI agent for physicians released broadly in July 2025), EvidenceGrade (surfacing the strength of cited evidence), a specialty oncology model incorporating ASCO guidelines, a HIPAA-secure Dialer communication tool, patient messaging, fax, ambient note generation with configurable "Voices," automated CPT/E-M/ICD-10 coding suggestions, reusable prompt "Dotflows," patient handout "Take-Homes," and a continuing education/MOC credit platform.
Founding story
Founded in 2022 by Daniel Nadler, a Harvard PhD, and Zachary Ziegler, a Harvard machine-learning researcher and PhD student, to address the difficulty physicians face in keeping up with rapidly growing medical literature. Nadler previously founded Kensho Technologies, acquired by S&P Global in 2018 for about $700 million, and invested $10 million of his own money into OpenEvidence.
Business model
Access to the platform is free for verified U.S. clinicians; revenue is generated from advertising. Pharmaceutical and medical device companies purchase five-second video ads within the application, delivered contextually based on the physician's search query. Management states most ad inventory remains deliberately unsold to preserve the user experience.
Advertising-supported. The company reported topping $100 million in annual/annualized revenue in 2025, and the CEO stated revenue could reach roughly $1 billion if all available ad inventory were sold.
Traction
The company reports use across more than 10,000 U.S. hospitals and medical centers and daily use by more than 40% of U.S. physicians. Monthly verified-physician consultations grew from roughly 358,000 in July 2024 to over 8.5 million in July 2025 and about 18 million in December 2025, versus about 3 million a month a year earlier. Registered U.S. physicians rose from more than 430,000 (July 2025) to 760,000 (December 2025), with roughly 65,000 new verified clinician registrations per month reported in mid-2025. The company states more than 200 million AI-powered clinical consultations have been supported to date and that over 100 million Americans are treated annually by a clinician using the platform.
Latest developments
Following the January 2026 Series D, the company said it would spend heavily on R&D and compute for its multi-agent architecture, additional content licensing, and specialist "medical super-intelligence" models, a thesis Nadler presented at the J.P. Morgan Healthcare Conference. The announcements page lists 2026 partnerships and launches including Cedars-Sinai (agentic, patient-aware clinical intelligence), NewYork-Presbyterian/Columbia/Weill Cornell, the American Academy of Pediatrics, Boston Children's Hospital, OneOncology, Springer Nature, the Los Angeles County Department of Public Health, the American Academy of Ophthalmology, the Society for Neuro-Oncology, the Society of Surgical Oncology, the Anticoagulation Forum and JOMI, plus product releases such as EvidenceGrade, a CE/MOC education platform, Patient Take-Homes, Coding Intelligence, Voices, Messages, Fax and Dotflows.
βΈFull profile β market position, technology, go-to-market, geography, history, risks & controversies
Market position
Described by the company and press coverage as the most widely used medical AI among verified U.S. clinicians and colloquially as "ChatGPT for doctors." A 2026 Offcall survey cited by Fierce Healthcare found OpenEvidence was the most used AI tool among doctors, at 45% of physicians β more than the other nine tools surveyed combined. Emerging competition includes OpenAI's ChatGPT Health and Anthropic's Claude Healthcare, both HIPAA-compliant consumer chatbot extensions.
Management cites first-mover advantage among physician-facing AI tools, a "copyright-friendly" licensing approach that grounds answers in journals clinicians already trust, exclusive verified-clinician focus, and a proprietary feedback loop from hundreds of millions of real-world clinical consultations.
Technology
A large language model-based platform that analyzes and organizes peer-reviewed medical literature from licensed journal sources; models are trained on medical journals and medical data rather than the open internet or social media. The company reports its model scored 90% on the USMLE in 2023 and 100% in 2025. Current architecture is described as multi-AI agentic, multimodal and multicloud, with plans for an "orchestra" of smaller specialist models (e.g., oncology, radiology, neurology) trained on real-world clinical consultation data and coordinated by a central routing or "conductor" model.
Go-to-market
Primarily organic, physician-to-physician adoption; the CEO states 95% of new users hear about the product from another physician. Registration requires NPI verification. Growth is supplemented by content licensing and institutional partnerships with journals, specialty societies, health systems and public health agencies.
Verified U.S. physicians and other frontline clinicians, including those in small practices without IT departments or software budgets; advertisers are pharmaceutical and medical device companies.
Geography
United States; headquartered in Miami, Florida, with the July 2025 funding announcement datelined Cambridge, Massachusetts. Wikipedia lists the area served as the United States.
History
After its 2022 founding, OpenEvidence reported a 90% USMLE score in 2023 and participated in the Mayo Clinic health-technology accelerator that year. It raised a $75 million Series A led by Sequoia Capital at a $1 billion valuation in February 2025, was named to the Forbes AI 50 list in April 2025, raised a $210 million Series B at a $3.5 billion valuation co-led by GV and Kleiner Perkins in July 2025 alongside the wide release of DeepConsult, raised $200 million in a Series C at a $6 billion valuation in October 2025, and closed a $250 million Series D at a $12 billion valuation in January 2026 co-led by Thrive Capital and DST. Total funding is approximately $700 million.
Risks & controversies
The company relies on an advertising model funded by pharmaceutical and medical device companies while serving clinical decision support, and depends on continued content licensing relationships. Wikipedia's reference list includes a June 2025 report titled "Medical AI Firm Says Competitor Hacked Prompts to Steal Secrets." Competitive pressure is emerging from OpenAI and Anthropic healthcare offerings. Nadler said he intends to keep the company independent despite acquisition interest and views an IPO as following foundation-model companies. Many usage and revenue figures are company-reported claims.
Compiled by commissioned research from 8 cited public sources β announcements, filings, and press listed under research sources below.
Key figures
latest reportedCompany-reported or press-reported figures, each dated to when it was claimed β not independently audited.
Founder mafia
5 people who came through OpenEvidence went on to found or lead other companies.
Competitors Β· 2
by search overlapCompanies competing with OpenEvidence for the same Google search keywords, organic and paid, via search-intersection analysis.
Timeline Β· 30
launches, deals, and filingsProceeds earmarked for model training, compute and content licensing partnerships; brings total funding to about $700 million.
$250M source β
Company team page lists Amaro founders and staff as having joined via acquisition by OpenEvidence.
Company team page lists Vocode founders as having joined via acquisition by OpenEvidence.
Agreement to make NCCN oncology guideline content available on the OpenEvidence platform.
$200M source β
Sequoia followed on; Coatue, Conviction, Greycroft and Thrive also participated. Company said it had raised more than $300 million since founding.
$210M source β
Described as the first AI agent purpose-built for physicians, using reasoning models to synthesize findings across multiple studies.
$75M source β
Dated company events from announcements, filings, and press; legal rows summarize public dockets and regulator releases.
In the news
βΈResearch sources Β· 8
primary sources listed
- About | OpenEvidenceopenevidence.com Β· web
8 public sources were cited for this profile; the first-party ones are listed here.
Frequently asked questions
- What does OpenEvidence do?
- AI medical search and clinical decision-support platform used free by verified U.S. clinicians, monetized through advertising.
- Who founded OpenEvidence?
- OpenEvidence was founded by Daniel Nadler, Zachary Ziegler.
- Who are OpenEvidence's investors?
- OpenEvidence's investors include Alkeon Innovation, Amity Ventures, Andreessen Horowitz, Breyer Capital, Catalio Capital Management, LP, Coatue Management, Cold Start Ventures, Conviction and 14 more.



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