Please note: This research project will be discontinued on 31 January 2024.
The application will no longer be available after this date. Information on this page will be provided for historical purposes only. Some portion of this content may be out-of-date and include broken links.

Please visit the OCLC Research website to learn more about our current research.

OCLC Cataloging and Metadata subscribers can use WorldShare Record Manager or the WorldCat Metadata API to perform similar searches to find classification numbers. ​


Classify is a FRBR-based prototype designed to support the assignment of classification numbers and subject headings for books, DVDs, CDs, and other types of materials.


This project applies principles of the FRBR model to aggregate bibliographic information above the manifestation level. Bibliographic records are grouped using the OCLC FRBR Work-Set algorithm to form a work-level summary of the class numbers and subject headings assigned to a work. You can retrieve a summary by ISBN, ISSN, UPC, OCLC number, author/title, or subject heading.

The Classify database is accessible through a user interface and as a machine-to-machine service. The database provides access to more than 46 million work summaries that contain Dewey Decimal Classification (DDC) numbers, Library of Congress Classification (LCC) numbers, or National Library of Medicine (NLM) Classification numbers. Classify records also include subject headings from the Faceted Application of Subject Terminology (FAST) scheme.


Click on the following examples or visit the prototype to view classification information and subject headings for a work.

link to The omnivore's dilema link to Persepolis link to Akahige link to Girl with Pearl Eering in Spanish link to On writing by Stephen King

Blog Articles

"Classify: A FRBR-based Research Prototype for Applying Classification Numbers." NextSpace, 14 (January): 14-15. Available online at:

Classify Web Service API

Beginning 31 October 2023 Classify API keys are no longer being issued.

Use of our prototypes is subject to OCLC's terms and conditions. By continuing past this point, you agree to abide by these terms.

Try the online demo


Visit the prototype - or click on the examples in the body of this page - to view classification information and subject headings for a work.