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CiteKit
Open Reference Library

Citation Link Checker

CiteKit's Citation Link Checker checks citation and reference links for accessibility, redirects, broken sources, and reference rot.

Paste links to check Up to 50 per check
Verification results
  • Checked citations appear here.

CiteKit Citation Link Checker checks supported citation links and identifiers to determine whether they resolve through the service or location expected for that input. A DOI is checked as a DOI, an ISBN is checked as a book identifier, a YouTube URL is checked as a video location, and an ordinary URL is checked as a web location.

The tool accepts multiple items at once and identifies the type of each submitted value before running the corresponding check. A successful result can include returned detail information and a canonical URL. A failed lookup is reported as not found. The batch result then reports the number of valid and broken items.

That distinction matters because citation-link verification is a resolution task. The checker asks whether an identifier or location can be resolved; it does not decide whether the underlying source is correct, authoritative, relevant, or sufficient evidence for a claim.

Concept relationships

  • DOI → identifies → Object
  • ISBN → identifies → Publication product
  • URL → locates → Web resource
  • Citation link checker → tests → Identifier or URL resolution
  • Verification result → describes → Resolution status

Persistent identifiers and web locations behave differently

A DOI is designed as a persistent identifier. DOI infrastructure associates the identifier with information about the identified object and allows that identifier to resolve even when the object's current location changes. [0]

Crossref exposes metadata for registered scholarly works through its REST API, which CiteKit can use when checking DOI inputs. [0]

An ISBN performs a different job. The International ISBN Agency describes an ISBN as an identifier for a specific monographic publication product. Different editions or formats can therefore carry different ISBNs. [0]

An ordinary URL identifies a web location rather than functioning as a bibliographic identifier system. HTTP defines the semantics of requests and responses used when a client checks that location. [0]

What a valid result means

A valid result means the submitted identifier or link resolved through the check CiteKit performed. For a DOI, that means the DOI lookup succeeded. For an ISBN, it means the book lookup returned a match. For a YouTube URL, it means the video check returned an available result. For an ordinary URL, it means the web request produced a response that the checker treated as accessible.

Those results are useful for finding malformed identifiers, unavailable pages, mistyped links, and references whose current location can no longer be reached. They are narrower than source evaluation. A valid DOI can point to a paper with weak evidence. An accessible webpage can contain outdated information. A matching ISBN identifies a publication product; it does not assess the book's claims.

Web citations can degrade after publication because resources move, disappear, or change. Research on scholarly reference rot found that a substantial share of cited web resources became unavailable or changed over time. [0]

The Citation Link Checker therefore complements citation generation rather than replacing it. The Citation Generator formats a reference. The Bibliography Generator formats a reference set. The Citation Link Checker tests whether supported identifiers and links still resolve.

Resolution is not validation of the source's argument. CiteKit does not infer that a source is reliable merely because its DOI resolves or its URL responds. The checker also does not establish that the cited source supports the sentence beside the citation, that the metadata is complete, or that the source is appropriate for the publisher's subject.

Source evaluation remains a separate editorial or research judgment. Link checking contributes one narrower signal: whether the identifier or location used by the citation can currently be resolved.

Sources

5 Sources

  1. 1. DOI Foundation, “DOI Handbook,” https://www.doi.org/doi-handbook/html/

  2. 2. Crossref, “REST API,” https://www.crossref.org/documentation/retrieve-metadata/rest-api/

  3. 3. International ISBN Agency, “What is an ISBN?,” https://www.isbn-international.org/content/what-isbn

  4. 4. Fielding, Roy T., Mark Nottingham, and Julian Reschke, “HTTP Semantics,” RFC 9110, Internet Engineering Task Force, https://www.rfc-editor.org/rfc/rfc9110.html, DOI: 10.17487/RFC9110

  5. 5. Klein, Martin, Herbert Van de Sompel, Robert Sanderson, Harihar Shankar, Lyudmila Balakireva, Ke Zhou, and Richard Tobin, “Scholarly Context Not Found: One in Five Articles Suffers from Reference Rot,” PLOS ONE 9, no. 12 (2014), https://doi.org/10.1371/journal.pone.0115253, DOI: 10.1371/journal.pone.0115253