OpenEvidence's doctor-first bet: free AI search to 758K doctors, $12B valuation

AI-powered medical search and decision-support platform that answers clinicians' questions from peer-reviewed journals and guidelines with citations; free to verified doctors and ad-supported.

That a free, citation-grounded AI search engine for verified doctors — not hospital CIOs — becomes medicine's default knowledge layer and monetizes at scale.

~$700M total: $210M Series B (Jul 2025, GV and Kleiner), $200M Series C (Oct 2025 at $6B, GV-led), $250M Series D (Jan 2026 at $12B, Thrive + DST)

After selling Kensho to S&P Global, Daniel Nadler co-founded OpenEvidence in 2021 with Zachary Ziegler in Miami, betting doctors wanted a conversational interface grounded in the same journals and guidelines they already used — not the open internet.

The free, ad-supported platform grew through verification-based signups — around 65,000 new verified US clinicians a month at the July 2025 Series B — passed $100M annual revenue and 18M monthly clinical consultations by December 2025, and launched DeepConsult and a HIPAA-secure Dialer. It raised $210M in July 2025, $200M in October 2025, then $250M in January 2026.

Still scaling: the Series D funds multi-agent 'medical superintelligence' and compute, and Nadler bets focus beats OpenAI and Anthropic health side-hustles.

A free product removes adoption friction for time-poor doctors, and verification creates a trusted, exclusive distribution channel.

Content licensing with the journals doctors already use made answers feel grounded, unlike general chatbots.

Bottom-up habit beats top-down sales: Nadler builds for doctors rather than hospital CIOs, turning daily usage into the moat.

Ad-supported economics with $100M+ revenue proved doctors as an audience monetize before big-ticket enterprise deals.

The open risk is generalist competition: OpenAI's ChatGPT for Health and Anthropic's Claude for Healthcare target adjacent segments.

Give the highest-trust users the free product first: if doctors make it their daily default, valuation follows — but the moat depends on content partners and habit against well-funded generalists.

As of September 2026, OpenEvidence remains privately held and scaling. The January 2026 Series D at $12B — double its October valuation — funds training, compute and content-licensing partnerships for an agentic 'medical superintelligence' platform, with oncology models flagged as the first specialty. The company says it is adding doctors at tens of thousands per month and continues to sign gold-standard journal partnerships, positioning itself as the default operating system of medical knowledge in the US.