Reference checker
Paste your reference list. Each reference is looked up in Crossref and comes back found, found with a different year or authors, or not found, and flagged if the paper has been retracted.
Up to 25 references a check, 3 checks a day.
How it works
Paste or upload
A reference list, a .bib or .ris file, or the whole draft as Word or PDF.
Each work looked up
In Crossref, where publishers register their papers, then OpenAlex for books and the rest, by DOI or by title, author and year.
See what to fix
Found, found with a different year or authors, or not found, and any retraction flagged.
Records from Crossref and OpenAlex; retractions from Retraction Watch, through Crossref. Nothing you paste or upload is kept.
Keep your library in Zotero?
Right-click items or a whole collection and choose Check references with hedwigai. The check opens here and starts at once. Free, for Zotero 7 and 8; nothing in your library changes.
What does the reference checker check?
Three things for each entry. Whether the work exists: a record in Crossref, or in OpenAlex for what Crossref lacks, with the same title. Whether the details are right: the first author and year agree with the record, a year either way allowed for online first and print. And whether it has been retracted or corrected, which Crossref records from Retraction Watch. Entries listed twice are pointed out too.
It reads APA, Vancouver, IEEE and Harvard, numbered or not, BibTeX and RIS. A DOI in the entry is looked up first; otherwise the whole entry is matched, so a two-word title like “Deep learning” finds LeCun, Bengio and Hinton’s paper and not the hundred others that share it.
Why would a reference not be found?
Because it does not exist, which is common in drafts written with an AI: in one study, 55% of the references GPT-3.5 wrote and 18% of GPT-4’s were invented. Or because it is a report, a thesis or a conference paper registered nowhere: what Crossref lacks is looked for in OpenAlex, which holds most books and theses too. The checker never calls a reference fake. Not found means look it up yourself.
What does the full check add?
A reference can exist and still be cited for something it does not say. Sign in and give hedwigai the whole draft: every reference is also searched for on the web, and every sentence that cites one, [3] or (Smith et al., 2020), is read against the work it cites, with the passage that settles it. Your words come back exactly as written. How the check works, on one draft.
What does it cost?
This page is free: 25 references a check, 3 checks a day. The full check is billed per reference, a few dollars for a thesis, and new accounts start with credit. How pricing works.