OCLC was founded in 1967 under the leadership of
Fred Kilgour. That same year, OCLC began to develop the union catalog technology that would later evolve into WorldCat; the first catalog records were added in 1971. In 2003, OCLC began the "Open WorldCat" pilot program, making abbreviated records from a subset of WorldCat available to partner web sites and booksellers, to increase the accessibility of its subscribing member libraries' collections. In October 2005, the OCLC technical staff began a
wiki project, WikiD, allowing readers to add commentary and structured-field information associated with any WorldCat record. WikiD was later phased out, although WorldCat later incorporated
user-generated content in other ways. In 2006, it became possible for anyone to search WorldCat directly at its open website WorldCat.org, not only through the subscription FirstSearch interface where it had been available on the web to subscribing libraries for more than a decade before. Options for more sophisticated searches of WorldCat have remained available through the FirstSearch interface. In 2017, OCLC's WorldCat Search
API was integrated into the cite tool of Wikipedia's
VisualEditor, allowing Wikipedia editors to cite sources from WorldCat easily. Beginning in 2017, OCLC and the
Internet Archive have collaborated to make the Internet Archive's records of digitized books available in WorldCat. In May 2022, OCLC announced WorldCat Entities, a new infrastructure for
library linked data. Maintenance of WorldCat Identities was suspended and the service will be discontinued as it is being replaced by WorldCat Entities. In August 2022, OCLC launched a "redesigned and reimagined" WorldCat.org website with the stated goal "to offer greater accessibility to the collections". The website now requires the use of
JavaScript and is therefore no longer accessible for users of older web browsers or those that have
JavaScript disabled for
security reasons. The update also removed users' book reviews and replaced them with reviews from
Amazon subsidiary
GoodReads. In 2023,
Anna's Archive scraped and began distributing the whole WorldCat database and was subsequently sued by OCLC in January 2024. ==System architecture==