LibraryThing

LibraryThing is a social cataloging web application for storing and sharing book catalogs and various types of book metadata. It is used by authors, individuals, libraries, and publishers.

Based in Portland, Maine, LibraryThing was developed by Tim Spalding and went live on August 29, 2005, on a freemium subscriber business model, because "it was important to have customers, not an 'audience' we sell to advertisers." They focused instead on making a series of products for academic libraries. Motivated by the cataloguing opportunities and financial challenges presented by the COVID-19 pandemic, the service went "free to all" on March 8, 2020, while maintaining a promise to never use advertising on registered users. As of February 2021, it has 2,600,000 users and more than 155 million books catalogued, drawing data from Amazon and from thousands of libraries that use the Z39.50 cataloguing protocol.