Disclosure: I built the Apify Actor linked at the bottom of this page, and it is paid. This page was drafted with an AI assistant. The Crossref endpoint and its CORS header were tested on October 5, 2026. The tool runs in your browser, sends nothing to my servers, and has no analytics or tracking.

Crossref, the registry that issues most scholarly DOIs, publishes each work’s metadata for free through a public JSON endpoint, no login required. One of the fields is is-referenced-by-count, the number of other Crossref-registered works that cite it. This tool asks Crossref for each DOI you paste and shows the title, that count, the year and the journal.

One DOI per line (commas also work). Plain DOIs or full doi.org links both work. Up to 25 at a time, sent to Crossref's public API straight from your browser, a few at once so the tool stays inside Crossref's normal usage.

What the fields mean

  • Citations is Crossref’s is-referenced-by-count: the number of other works registered with Crossref that cite this one. It is not the same number as Google Scholar, Scopus or Web of Science, which index different sources, so treat it as one data point, not the final word, and say where it came from if you quote it.
  • not found means Crossref has no record for that string as a DOI. Check for a typo, or the DOI may belong to another registration agency such as DataCite (common for datasets), which Crossref does not cover.
  • Counts change over time. The number you see is live at the moment you click, not cached.

How it works, and what it does not do

Your browser sends one GET request per DOI straight to api.crossref.org/works/<doi>, four at a time, with a mailto parameter identifying this site so Crossref’s polite pool handles the requests. Nothing is stored and nothing is sent to this site; there are no cookies, analytics or third-party scripts on this page. The tool checks up to 25 DOIs per click, pasted by hand, which is what the free public API is for. It does not search by keyword, author or journal, and it does not fetch abstracts or reference lists.

Need more than 25 at a time, on a schedule, or without typing them in?

For a list of DOIs read from a file, a run larger than you’d paste by hand, or a lookup that repeats on a schedule, I built a paid Apify Actor, Crossref Works Search. Give it up to 10,000 DOIs in one run (as a list, a CSV column or doi.org links) and it returns one row per work as JSON or CSV, with no copy-pasting into a browser form. It also doubles as a search tool, finding works by keyword, author, journal, funder or date range when you don’t have DOIs yet. On the base price tier it is charged per work found; check the current price on the Actor page. For the Python version of the same free lookup, see DOI Citation Count Bulk Lookup in Python.