Based in Portland, Maine,[1] 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."

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 never to use advertising on registered users.

The primary feature of LibraryThing (LT) is the cataloging of books, movies, music and other media by importing data from libraries through Z39.50 connections and from six Amazon.com stores.

Members are encouraged to add publicly visible reviews, descriptions, Common Knowledge and other information about a work; ratings, collections, and tags help categorization.

[13] In January 2009, Cambridge Information Group acquired a minority stake in LibraryThing, and their subsidiary Bowker became the official distributor to libraries.