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WorldCat » WorldCat Affiliate tools » xISBN (Web service) » FAQ

xISBN (Web service)

Use this Web service to map book-related identifiers (ISBN, LCCN, OCLC number), based on WorldCat information. Free and subscription versions are available.

Frequently Asked Questions: xISBN

What is the xISBN Web service?

xISBN is a Web service that supplies International Standard Book Numbers (ISBNs) associated with an individual intellectual work, based on information in the WorldCat database. Give it one ISBN, and it returns a list of related ISBNs and selected metadata.

What are "related ISBNs"?

They are ISBNs of other editions or version of the same "work." For example, given the ISBN of the U.S. hardcover edition of The Da Vinci Code, associated ISBNs returned by this Web service might include those for the U.S. paperback; library-bound or large-print editions; audiobooks; foreign editions; and possibly out-of-print editions.

Why would I want to retrieve related ISBNs?

Books are usually referenced by ISBN. However, a user looking for a book usually isn't trying to find a specific edition—they would like to see all versions of the source work. For example, an end user may have an ISBN representing a trade paper edition, but you would like your online application to reference all versions that are in print, or in a library's case, all versions in its collection.

Is this Web service available now?

Yes. You can try it by entering the following address in a Web browser:


where [ISBN] is a recognized ISBN. For example,

will return a list of ISBNs for editions of Frank Herbert's Dune.

Is xISBN free?

There is no charge for low-volume, non-commercial use of the xISBN service. Commercial use or high-volume use (more than 500 requests per day) of the xISBN Web service is possible by order.

In what ways is the xISBN service provided?

First, as an XML Web service, via the simple URL-based protocol that is currently deployed. We also add OpenURL 1.0 and unAPI based interfaces as well. Subscription-based use is available in three types:

  1. Data file: intended for high-volume local use in environments where use of a Web service is impractical.
  2. Token-controlled query use: a token (e.g. 100,000 access) is issued, you can take however long you want to use them.
  3. IP address-controlled use: A daily quota (e.g.1000 queries per day) is associated with your IP address.

How to make an order?

You must first create a WorldCat Affiliate account, and Sign in to place an order.

Once you enter an order, we will get in touch with you to process the new order. Meanwhile, an invoice will be issued and shipped to your billing address from OCLC Finance or OCLC Regional Service Providers

How often is xISBN data updated?

The xISBN data set is regenerated from Worldcat on a monthly basis.

Does xISBN utilize FRBR?

Yes. FRBR (Functional Requirements for Bibliographic Records) is a model for grouping bibliographic records, and is widely accepted in the library and cataloging communities. The algorithms used to generate associated ISBNs in this service are based on FRBR.

I've also heard talk about "xID." What is that?

xID or xIdentifier is a categorical term that has been applied to services such as xISBN which perform grouping of related identifiers, such as ISBN or ISSN.

Is there a mailing list I can subscribe to keep informed about xISBN and other xID services?

Yes. To join the mailing list via OCLC's LISTSERV® application, please visit

How can I learn more about my organization using or licensing xISBN?

Please contact OCLC Openly at, or call or call (973) 509-7800 (U.S.), for more information.

Does the original OCLC Research Web service still work?

xISBN originated from an OCLC Research project conducted by Jenny Toves and Thom Hickey. This version of the Web service was available from:[ISBN]

This address continues to function, but developers are urged to begin using new API. The API document of old-xisbn is available from here.

What happens if my application makes too many requests?

The xISBN service is designed to always return valid XML. If you make too many requests, the service will return a message with overlimit flag.