VI · 41

OpenURL & Crossref

Crossref runs an OpenURL endpoint that returns citation metadata for a DOI or matches descriptive metadata to a DOI.

Crossref, the largest DOI registration agency for scholarly content, operates an OpenURL endpoint at doi.crossref.org/openurl. The endpoint accepts OpenURL-syntax requests and returns metadata about the registered DOI matching the request. It is widely used by citation managers, indexers, and discovery systems to fetch metadata for a known DOI or to match descriptive metadata to a DOI.

Endpoint

https://doi.crossref.org/openurl

Requests are HTTP GET. Most callers send standard OpenURL parameters, sometimes mixed with Crossref-specific options.

Common parameters

ParameterPurpose
pidRequired: your email address. No account or key is needed; Crossref uses the address to contact you about problems with your requests.
idDOI lookup, in the form doi:<DOI>.
noredirect / redirectReturn XML metadata instead of redirecting to the DOI's landing page.
multihitIf true, return several candidate matches when there is no single exact match.
formatResponse format: unixsd (modern Crossref schema) or unixref (legacy schema).
rft_idStandard OpenURL identifier carrying info:doi/<DOI>.
rft.*OpenURL 1.0 metadata keys (rft.jtitle, rft.aulast, rft.volume, rft.spage…). The 0.1 forms (title, issn, aulast, volume, issue, spage, date, stitle) also work. A metadata query needs at least an ISSN or title plus a start page or author.

Example request

A descriptive-metadata lookup, asking for the unixsd-format response:

https://doi.crossref.org/openurl?
pid=your-email%40example.org
&rft.atitle=Can+Quantum-Mechanical+Description+of+Physical+Reality+Be+Considered+Complete%3F
&rft.aulast=Einstein
&rft.jtitle=Physical+Review
&rft.date=1935
&rft.volume=47
&rft.spage=777
&noredirect=true
&format=unixsd

A DOI lookup:

https://doi.crossref.org/openurl?
pid=your-email%40example.org
&id=doi:10.1103/PhysRev.47.777
&noredirect=true
&format=unixsd

Notes

  • Use a real, monitored email address in pid. Crossref may reduce service to clients without one.
  • For high-volume metadata retrieval, Crossref's REST API (api.crossref.org) is generally a better fit. The OpenURL endpoint exists primarily for compatibility with OpenURL-based citation tools.
  • Crossref's OpenURL endpoint is documented at the URL listed in the Sources section below.

Sources