Crossref
Crossref is the nonprofit DOI registration agency that most scholarly publishers deposit their metadata with. Through ScholarMuse an agent can check a reference list against Crossref records, look up the registered metadata of a DOI, read the retraction, correction and expression-of-concern notices attached to it, and search Crossref by citation text when asked to.
ScholarMuse tools: verify_references, check_retractions, get_paper, search_papers. Each successful call uses credits.
The web tools run without an account, up to 5 runs a day per visitor.
Ask your agent
What your agent gets back
Every record carries id, source, title, url, license, attribution and retrievedAt. The fields below are the data that comes from Crossref.
verify_references
Crossref is treated as the record of reference for metadata. OpenAlex is checked alongside it.
- status
- verified, corrected, not_found or uncertain
- matchedBy
- How the match was made: doi, pmid, arxiv or title
- titleSimilarity
- Title similarity between cited and found, 0 to 1
- corrections
- Differing fields: doi, year, first_author, journal, volume, pages
- retracted
- True when the matched paper is retracted
- retraction
- Retraction notice: type, notice DOI, date and source
- parsed
- What was read from the reference as cited
- matched
- Registered metadata of the matched paper
- notes
- Plain-language remarks on the check
check_retractions
Notices come from the Crossref updated-by field, which holds publisher deposits and Retraction Watch entries.
- doi
- The DOI that was checked
- status
- retracted, expression_of_concern, corrected, no_notice or not_found
- retracted
- Combined retraction verdict
- expressionOfConcern
- True when an expression of concern is attached
- corrected
- True when a correction or erratum is attached
- notices
- Each notice: kind, type, noticeDoi, date, source
- crossrefRetracted
- Crossref's own retraction verdict for the DOI
- year
- Publication year
- journal
- Journal name
- notes
- Remarks, such as a DOI not registered with Crossref
get_paper
Only for DOIs, and only when OpenAlex has no record for the DOI.
- doi
- DOI in lower case
- authors
- Author names, first 12
- year
- Publication year
- date
- Issued date
- venue
- Journal or book title
- volume
- Volume
- issue
- Issue
- pages
- Page range
- publisher
- Publisher name
- type
- Crossref work type, such as journal-article
- citedBy
- Crossref is-referenced-by count
- retracted
- True when a retraction notice or title flag exists
search_papers
Crossref is searched only when the agent names it in sources.
- doi
- DOI in lower case
- authors
- Author names, first 12
- year
- Publication year
- venue
- Journal or book title
- volume
- Volume
- issue
- Issue
- pages
- Page range
- publisher
- Publisher name
- type
- Crossref work type
- citedBy
- Crossref is-referenced-by count
- abstract
- Abstract when the publisher deposited one
What it covers
- Works with a DOI registered at Crossref: journal articles, books, chapters, proceedings and more.
- Retraction, correction and expression-of-concern notices from the updated-by field, including Retraction Watch entries.
- DOIs registered elsewhere, such as DataCite or arXiv DOIs, are not in Crossref. The tools say so in their notes.
Limits
- verify_references checks at most 50 references per call and check_retractions at most 100 DOIs.
- check_retractions only checks references that contain a DOI. References without one go through verify_references.
- In search_papers Crossref is opt-in and returns at most 25 results. With open_access_only it keeps only works that carry a Creative Commons licence.
- Crossref has no open-access link, so openAccessUrl is never filled from it. Abstracts exist only when the publisher deposited them.
How ScholarMuse reaches Crossref
The connector calls api.crossref.org/works directly: a bibliographic query for searches, a single-work request per DOI, and a DOI filter in groups of 20 for batch checks. No API key is sent. Requests carry a contact email, as Crossref asks of polite clients.
Searches are cached for up to 6 hours and DOI lookups for up to 1 day, so a notice registered today can take a day to appear.
API key: the upstream API can be called without one, so you do not add one.
Licence and attribution
Licence: Crossref metadata: facts, free to reuse (abstracts may be under publisher copyright)
Metadata from Crossref (crossref.org), including Retraction Watch data.
Records that come from Crossref carry this licence and attribution. When you cite the data in a paper, follow Crossref's own citation guidance.
