Free tool · Open source (MIT) — Studio project, 2026
RefExists
Paste a bibliography; your browser checks every reference against six scholarly registries. Catches fabricated DOIs, AI-hallucinated citations and retractions. Free for everyone.
Paste a bibliography; your browser checks every reference against six scholarly registries. Catches fabricated DOIs, AI-hallucinated citations and retractions. Free for everyone.
AI writes confident citations. Some of them don’t exist.
Fabricated DOIs, hallucinated papers, "stitched" citations that weld a real author to a real journal and a paper that was never written — they all look fine on the page. RefExists checks. Paste a bibliography and the browser itself verifies every reference against Crossref, DataCite, doi.org, OpenAlex, PubMed and Open Library, flagging what is real, what is retracted and what was never there.
It is MIT-licensed and free for everyone — and because verification runs 100% client-side, your bibliography never touches our servers. It can’t: the CSP forbids it.
A tool about trust has to be structurally unable to betray it.
One input, checked across 250M+ scholarly works — DOIs resolved, metadata compared, retractions surfaced.
Detects the tell-tale LLM "stitched citation" signature — plausible fragments of different real works fused into one fake reference.
Ships with a keyless local MCP server exposing verify_citations, so AI agents can check their own homework.
The two hard problems were privacy you can prove and honesty about absence.
A strict Content-Security-Policy allowlists only the six registry origins. The browser is physically prevented from sending your text anywhere else — enforced, not promised.
A network failure is not the same as "this paper doesn’t exist". A reference is only marked missing after a definitive registry 404 chain — the engine distinguishes "couldn’t check" from "checked, and it’s not there".
A 25-case test suite runs against the real registry APIs, covering the fabrication patterns we actually see.
RefExists is our kind of public service: MIT-licensed, free, and incapable of spying on you — a small sharp tool for the exact moment this decade needed one.