Citation checker

Paste a reference list and this citation checker looks up each entry in CrossRef and OpenAlex, the two big open catalogues of research. You see which references exist, which have the wrong year or author, and which can't be found anywhere, which is what an AI-invented reference looks like. No account needed.

Example result

1 found1 to check1 not found

1Found
LeCun, Y., Bengio, Y., & Hinton, G. (2015). Deep learning. Nature, 521(7553), 436–444. https://doi.org/10.1038/nature14539
CrossRef record LeCun, Bengio, Hinton (2015). Deep learning. Nature. doi.org/10.1038/nature14539
2Found, details differ
Kahneman, D. (2013). Thinking, fast and slow. Farrar, Straus and Giroux.
Year: you wrote 2013, the record says 2011.
OpenAlex record Kahneman (2011). Thinking, Fast and Slow
3Not found
Smith, J. A., & Carter, L. M. (2021). Adaptive neural scaffolding for cross-lingual sentiment transfer in low-resource classrooms. Journal of Educational Data Science, 14(3), 211–229. https://doi.org/10.1016/j.jeds.2021.04.012
The DOI 10.1016/j.jeds.2021.04.012 is not registered.
No paper, book or report with this title in CrossRef or OpenAlex (over 250 million records). AI tools often invent references like this. It can also be a thesis, a very new preprint or a source these databases do not cover.

How to use the citation checker

Copy your reference list from Word, Google Docs, LaTeX output or a reference manager. Keep each reference on its own line or paragraph; numbers like [1] or 1. are fine.
Paste it and press Check references. Results appear one by one, usually in two or three seconds per reference.
Fix the red and amber marks. Each result shows the record that was found, with its DOI link, so you can compare it with what you wrote.

What the marks mean

✓ Found: A record with the same title, first author and year (give or take one year, since online-first and print dates differ).
? Found, details differ: The work exists, but the year or first author you wrote doesn't match the record. Often a typo, sometimes a sign the reference was pieced together from two papers.
? Close match only: The nearest record has a similar but different title. Open it and make sure it is the work you meant.
✗ Not found: No matching paper, book or report in either database, or a DOI that is not registered. Treat it as unverified until you can open the source yourself.
– Web page, not checked: Plain web links aren't in these catalogues. Click through to confirm the page still exists.

Why made-up references slip into papers

Chatbots write references the same way they write sentences: by predicting what a plausible one looks like. The result has real-sounding authors, a fitting journal and sometimes a DOI with the right publisher prefix, but no such paper exists. In 2023 two New York lawyers were fined $5,000 after filing a brief with court cases ChatGPT had invented (Mata v. Avianca). Students and researchers run into the same problem when a chatbot helps with a literature review.

Checking by hand means searching every title in Google Scholar. With 40 references that is most of an afternoon. This tool does the same search against the publishers' own records and puts the doubtful ones at the top of your attention.

How the citation checker works

Each reference is split out of the pasted text, then:

If it has a DOI, the DOI is resolved at CrossRef. An unregistered DOI, or one that points to a different title, is reported.
The full reference is searched in CrossRef's bibliographic search (over 150 million records registered by publishers).
If that gives no strong match, the title is searched in OpenAlex (over 250 million works, including conference papers and preprints).
The best record is compared word by word with your title, and its first author and year with yours.

Both databases are free and public. The requests go from your browser, so your list never touches our server. For the APA style rules, use the APA format checker, which runs the same lookup and adds APA 7 format notes.

What it can't check

Theses and dissertations, many books published before 1990, and sources in languages other than English are often missing from CrossRef and OpenAlex.
Whether the source actually says what you cite it for. Only reading it tells you that.
Web pages, news articles and datasets without a DOI.

FAQ

Is this citation checker free?

Yes. You can check up to 25 references at a time, as often as you like, without an account. A paid Pro version for whole theses is planned; the free check will stay.

Do you store my references?

No. Your browser sends each reference directly to the public CrossRef and OpenAlex search services and shows you the answers. Nothing passes through our server.

Can it tell whether ChatGPT wrote a reference?

It cannot see who wrote a reference. It checks whether the work exists and whether the authors and year match. A made-up reference from ChatGPT or another AI tool usually comes back as Not found, or as a DOI that belongs to a different paper.

Which citation styles does it read?

APA, MLA, Chicago, Harvard, IEEE, Vancouver and most journal house styles. It does not rely on the style: it searches with the whole reference and then compares the title, first author and year it finds with what you wrote.

A real reference came back as Not found. Why?

CrossRef and OpenAlex cover journal articles, books, chapters, conference papers and many reports, but not every thesis, older book, non-English source or brand-new preprint. If you can open the source yourself, it is real; the mark only means the databases have no record of it.

Does it check in-text citations?

Not yet. Paste the reference list or bibliography at the end of your paper. Matching in-text citations to the list is on the Pro list.