Archive of Our Own - online puzzles

Archive of Our Own (AO3) is a nonprofit open source repository for fanfiction (fic) and other fanworks contributed by users. The site was created in 2008 by the Organization for Transformative Works and went into open beta in 2009. As of 2018, Archive of Our Own hosted over 3.7 million works in over 27,800 fandoms. The site has received positive reception for its curation, its organization, and the design of the site, mostly done by readers and writers of fanfiction.