DOI checker
Paste DOIs, one a line, or whole references with their DOIs. Each DOI is looked up where it is registered and comes back with the paper it names, not registered, or registered to a different title, and flagged if the paper has been retracted.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 DOI checker check?
That each DOI exists, and what it names. A DOI is looked up in Crossref, where most journals register theirs, and then at doi.org, which answers for every registry. You get the title, authors, year and journal on record, with a link. A DOI neither knows is marked not registered.
What if I paste the whole reference with its DOI?
Then the DOI is checked against the rest of the reference. A DOI registered to another paper is said, with the title it is registered to: the commonest mistake in a reference list typed or generated by hand, one wrong digit away from a real paper. A different year or first author is said too.
Does it check arXiv, Zenodo and dataset DOIs?
Yes. Those are registered with DataCite, not Crossref, so they are read from doi.org: arXiv’s 10.48550 DOIs, Zenodo’s 10.5281, and the DOIs most data repositories issue.
How does it know a paper was retracted?
Crossref records retractions, corrections and expressions of concern against the paper’s DOI, including Retraction Watch’s database, which it took over in 2023. A retracted paper is flagged with the year, and a correction is noted.
What does it cost?
This page is free: 3 checks a day, up to 25 DOIs each. For more, sign in: hedwigai checks a whole reference list, searches the web for what no registry has, and reads each sentence that cites a work against the work. That is billed per reference, and new accounts start with credit.