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WorldCat Metadata API 2.0 release notes, October 2023


Release Date: October 30, 2023


This release of the WorldCat Metadata API 2.0 provides the following enhancement:

  • Identify the most popular Library of Congress and Dewey classification numbers for a given OCLC Number with the new "classification-bibs" search endpoint.

New features and enhancements

Classification Endpoint 

GET /search/classification-bibs/{oclcNumber} 

Given an OCLC Number as input, the new endpoint will return the most popular Library of Congress and Dewey classification numbers. The query looks at the OCLC "work cluster" that the OCLC Number is part of and returns the LC and Dewey classifications from the record with the most institution holdings within that work cluster.

Example response:

  "dewey": {
    "mostPopular": [
  "lc": {
    "mostPopular": [
      "HM742 .H55 2010"

Important links

WorldCat Validation release notes

WorldCat Validation release notes provide current OCLC-MARC updates; changes to tagging conventions and coding practices for Bibliographic, Authority, and Holdings records; and new MARC codes. 

Virtual AskQC office hours

Join OCLC Metadata Quality staff to discuss WorldCat quality issues and cataloging questions. Visit AskQC for information about upcoming office hours, previous office hour recordings, and supporting materials.

Support website(s)

Support information for this product and related products can be found at: