How to tell if ChatGPT's citations are real
Updated October 9, 2026 ยท By Otter Potter, the maker of Cite Check (not neutral; we say where it matters).
Ask ChatGPT, Claude or Gemini for sources and you get a tidy reference list: plausible authors, a real journal, a year, sometimes a DOI. Some of those sources don't exist. Others are real papers with the wrong title, year or authors, or a real DOI that points to a different paper. The model writes what a reference usually looks like; it doesn't look the reference up unless it's searching the web, and even then the details can drift.
This is no longer a rare embarrassment. A database of AI-invented authorities in US court filings counted 524 cases in 2025 and 668 more in 2026 by late July, according to the Maryland State Bar Association. Students and consultants are caught the same way, just less publicly.
1. Check each one by hand (free)
Each check takes a minute or two. Do them for every reference you plan to keep.
- Has a DOI? Paste it after
https://doi.org/. If it loads, compare the title, authors and year on the page with what the AI wrote. A real DOI attached to the wrong paper is one of the most common AI mistakes. - No DOI? Search the exact title in quotes on Google Scholar or Crossref search. No match for the exact title, the author and a year near it is a strong sign it was invented.
- A book? Look up the ISBN or title on Open Library or WorldCat, and check the author and publisher.
- A US court case? Search the citation (for example
410 U.S. 113) on CourtListener. Make sure it leads to the case named, not a different one. - A link? Open it. A page that doesn't load, or loads something unrelated, isn't a source.
Then the step no tool does for you: read the source, or at least the part you're citing. A real paper can still not say what the AI claims it says.
2. Ask for sources you can click
AI tools that search the web while answering attach links to what they say. That makes checking faster, because you can open each one. It doesn't make checking optional: links can point to a page that doesn't support the sentence, and a reference list written after the search can still contain a made-up entry.
3. Cite Check (we make this)
Cite Check is a browser extension that does the checks in step 1 for a whole list at once. Select a reference list, or any text with citations, right-click, and it marks each source as found, not found, or found with different details. It matches titles, years and first authors against Crossref, OpenAlex and Open Library, looks up DOIs, arXiv and PubMed IDs and ISBNs directly, and with Pro and a free CourtListener token checks US case citations. Free for 20 citations a day; Pro is $29 a year.
What it can't do: it confirms that a source exists and that its details match the record. It doesn't tell you whether the source supports the claim; that still takes reading it. If a database can't be reached it says "Can't check" rather than guessing.
Questions
- Why does ChatGPT make up citations?
- It writes text that fits the pattern of an answer, and reference lists are a very regular pattern. Without looking each source up, it can produce one that fits the pattern perfectly and doesn't exist.
- If a source is "not found", is it definitely fake?
- Usually, but not always. Local reports, some conference papers and older books are missing from the big databases. Treat it as "find this before you rely on it".
- Is Cite Check made by OpenAI?
- No. It's made by Otter Potter and is not affiliated with OpenAI or any of the databases it checks.