Founded in 2009 by Luis von Ahn and Severin Hacker as an academic project, Duolingo, Inc. is an American educational technology company headquartered in Pittsburgh. It is known for its language learning apps and language certification services, offering courses in 42 languages, including constructed ones, to over 500 million users. The platform utilizes gamified, microlearning lessons and provides the Duolingo English Test and Duolingo ABC, a literacy app.