OpenEvidence

What is OpenEvidence and who sells it?

OpenEvidence answers clinical questions with cited literature. Its home page calls it "America's Official Medical Knowledge Platform" and lists partnerships with the New England Journal of Medicine, JAMA and the JAMA Network journals, Nature, and an AI collaboration with NCCN whose content includes the NCCN Guidelines treatment algorithms (OpenEvidence website, read October 2026). Access is for verified US clinicians.

The company is OpenEvidence, run by Daniel Nadler, previously of Kensho, and Zachary Ziegler. CNBC dates the founding to 2022. Tracxn says 2021, so we give the year as 2021 or 2022. Press reports give this funding history: $75M from Sequoia at a $1B valuation in February 2025, a $210M Series B at $3.5B in July 2025, a $200M Series C at $6.1B in October 2025, and $250M at $12B in January 2026. A further $250M at $15B was reported in September 2026 and the company has not confirmed it. These are press figures, not OpenEvidence statements.

Revenue comes mostly from pharmaceutical advertising, and Sacra estimates annualised revenue at about $300M in July 2026. OpenEvidence's privacy banner says it shares limited information with third parties to measure advertising and that it does not sell or share users' searches.

What does OpenEvidence do well?

It answers a clinical question in seconds with references you can open. The home page suggests three kinds of prompts: write home care instructions, compare treatment alternatives, and research a topic. The listed partnerships with NEJM, the JAMA Network and Nature are the selling point, since they put those journals behind the citations.

Reported use is the other signal. A family physician on r/FamilyMedicine (August 2025) wrote that using DAX Copilot and, more recently, OpenEvidence had raised their productivity and quality of care. A separate r/FamilyMedicine thread (January 2026) is titled "My favorite OpenEvidence feature". In the January 2026 outage thread, a commenter said they would spend a large share of their CME funds to keep the service from going down again, and compared it with UpToDate's AI at roughly $700 a year.

Price is part of the case. OpenEvidence is free for NPI-verified physicians, and STAT News (January 2026, as relayed by a CME site) reports it is free to any clinician with an NPI. No paid tier is listed.

The security page states HIPAA compliance, a standard Business Associate Agreement for PHI, a SOC 2 Type II report for the Security category, AES-256 encryption at rest, TLS in transit, hosting on Google Cloud Platform and Vercel, and an annual penetration test. HITRUST and ISO 27001 are not stated there.

Where does OpenEvidence fall short?

The complaints are about accuracy and source selection, and they come from clinicians, not competitors.

In September 2025 a post on r/emergencymedicine titled "OpenEvidence inaccuracy" told readers to "beware what OpenEvidence tells you" and described catching an error: a chest x-ray cannot be used to rule in or out a pulmonary embolism. On r/Residency the same month, a thread called "OpenEvidence Bias" asked whether the tool had become more biased, choosing certain journals even when a paper did not fit the age group in the question. How often either problem occurs is unknown. Both fit what the formal evaluations below show: the tool is useful and fallible.

Some limits are about scope. A competitor's review says OpenEvidence has no differential generator, dosing calculator or interaction checker. The same review reports that the company withdrew from the EU and UK in April 2026.

Whether advertising appears inside answers, and how it is labelled, is unclear. The product pages show no ads, and a free, ad-funded product raises the question.

How does OpenEvidence compare with UpToDate and ChatGPT?

The most direct rival is UpToDate with its AI features. Other products in the same category include DynaMed, ClinicalKey AI, Doximity GPT, Vera Health, Glass Health, DxGPT and Isabel. Web comparisons also set it against ChatGPT.

On price, UpToDate is a paid product. One commenter on r/FamilyMedicine (January 2026) put its AI-enabled access at about $700 a year. OpenEvidence is free for a verified clinician, with advertising paying for it.

On accuracy, the head-to-head evidence is thin. NYU Langone, in Nature Medicine (June 2026), reported 89.6% for OpenEvidence against 88.4% for UpToDate Expert AI on MedQA, and a one-point gap on a multiple-choice benchmark is not a basis for choosing a reference tool. A medRxiv preprint from November 2025, not peer reviewed, tested subspecialty scenarios and reported accuracy of 31% for a quick search and 39.5% for the Deep Consult mode. Deep Consult is not confirmed on an official OpenEvidence page.

For "what does the literature say about X", OpenEvidence is a free first pass. Whether a hospital's legal or quality team accepts it as a reference of record is that team's call. For documentation, none of this applies.

What does the evidence say?

The evidence is a set of external comparisons, not trials of patient outcomes. Five 2026 papers mention the tool. A Southern Medical Journal observational study compared GPT-4o, Perplexity AI and OpenEvidence on diagnostic radiology board-style questions (PMID 41999647). The Knee published a concordance study of ChatGPT, Gemini, Claude and OpenEvidence against the 2024 AAOS meniscal pathology guideline (PMID 41865615). The Journal of the Medical Library Association reviews the tool (PMID 41777900), the Journal of Medical Internet Research analysed how AI tools handle retracted literature (PMID 42066286), and the Journal of Clinical Medicine studied how language models promote minimally invasive interventional radiology in gynecology and obstetrics (PMID 42122968). None reports patient outcomes.

The retracted-literature study bears most on a tool whose pitch is citations. A sixth paper, indexed as PMC11787857, looked at OpenEvidence for medical student rotations and concluded it works "with limitations".

No randomised trial shows that using OpenEvidence changes a clinical decision or a patient outcome. The accuracy figures come from exam-style questions and small scenario sets, and the lowest (31% and 39.5%) is from a preprint.

Who should use OpenEvidence?

A resident on nights who wants a cited starting point for a guideline question, and will open the reference before acting on it, loses nothing by trying it, since it is free. A family physician who already pays for a reference and wants a faster search layer on top fits too. A clinician in a department that bans ad-funded tools should ask the compliance team first, because the advertising model is the sticking point, not the security page.

It is the wrong tool for anyone outside the US, anyone who needs EHR integration, and anyone who would paste an answer into a note without opening the cited paper.

The verdict

OpenEvidence earns a place as a free lookup tool. Public evidence of accuracy is mixed and mostly from benchmarks, so treat an answer as a pointer to papers and read the paper. As of October 2026 there is no public price list. The product is free for NPI-verified physicians and funded by advertising.