Dr. Ajith Kumar V.V
In a city obsessed with machine learning, one of the hottest companies in Pittsburgh is making humans Smarter. That Company is Duolingo, which offers online instruction in more than 30 languages, delivered as bite-size lessons in game formats. The business--with 2018 revenue of $40 million and a valuation of $700 million--makes money from advertising and some paid services. That model works because of Duolingo's outsize reach. After being named Apple's free iPhone app of the year in 2013, it has amassed more than 300 million users, becoming the world's most downloaded education app with zero advertising. It has done so by being free, fun, and effective.
Source: https://www.inc.com/leigh-buchanan/duolingo-700-million-language-learning-startup-pittsburgh-2018-surge-cities.html