Citation checker
Paste your draft with its reference list, or upload it as Word or PDF. Every citation in the text is matched to the list, and every entry in the list is looked up in Crossref.
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 citation checker check?
Two lists against each other, then the list against the record. In the text: every numbered citation, [3] or [3–5], and every author–year one, (Smith et al., 2020) or Smith (2020). In the list: every entry under References, Bibliography or Works cited. You get the citations with no entry, the entries nothing cites, and for each entry whether Crossref has it as you wrote it, and whether it has been retracted.
Why do citations and references stop matching?
Drafts change. A paragraph is cut and its source stays in the list; a section moves and its numbers no longer point where they did; a reference manager is out of step with the document. And AI writing tools cite works that are not in the list at all, or list works the text never uses.
Does it check that a citation supports the sentence?
Not here. That is the full check: sign in and hedwigai reads each sentence that cites a work against that work, and marks it supported, contradicted or unsupported, with the passage that settles it. The claim checker says more.
What does it cost?
This page is free: 3 checks a day, with up to 25 references looked up each time and every citation matched. The full check is billed per reference, and new accounts start with credit.