OCLC Research developed an experimental service that provided a list of items similar to an item of interest. The prototype service uses various characteristics of a sample work, such as classification numbers, subject headings, and genre terms, to retrieve related resources from WorldCat. This approach was called content-based recommendation.
The recommendations were accessible through a user interface and through an application programming interface (API). The user interface, Kindred Works, provided basic search functionality; users could search by author, title, ISBN, or OCLC number. The recommendations might have included books, ebooks, audiobooks, music, and video materials.
The recommendations could be customized to the collection of an individual library by adding the library’s OCLC holding symbol to the query. This feature was limited to libraries that participate in WorldCat.org. The API was intended to be used by software developers to integrate recommendations into another service or application, for example, a library catalog or other discovery interface.