AO3dle is a free online game for fanfiction enthusiasts that tests players’ knowledge of character popularity on Archive of Our Own (AO3). In each matchup, players choose which of two characters has more fanfiction works, then see the actual counts and build a streak with correct answers. The game draws on AO3 work data and features characters from a range of franchises and other works.

Players can choose from modes including daily challenges, which present a shared set of comparisons, and endless play, where matchups continue and difficulty can increase. Settings offer options such as difficulty levels, franchise filters, and AI-content filters. AO3dle also provides global rankings, score sharing, and guides to help players understand the game.

Designed for desktop, tablet, and mobile browsers, the game requires no download or registration and is free to play. Its quick rounds combine trivia, strategy, and competition, giving players a way to compare their knowledge with friends and other fans worldwide.