The xISBN web service supplies ISBNs and other information associated with an individual intellectual work that is represented in WorldCat. Submit an ISBN to this service, and it returns a list of related ISBNs and selected metadata.

Ideal for web-enabled search applications—such as library catalogs and online booksellers—and based on associations made in the WorldCat database, xISBN enables an end user to link to information about other versions of a source work.