Language learning mobile app Duolingo has just closed a $20-million round led by Kleiner Perkins Caufield & Byers, according to Forbes.

Duolingo says it currently has more than 10 million monthly users and has reached over 20 million downloads. A fourth of its users come from the US, its biggest market right now. However, data from App Annie show that the app is also popular in other European and American countries where English is not spoken. The app works like a game where players unlock different skills in a language program. According to founder Luis von Ahn, playing for a 34-hour play session with Duolingo is equivalent to attending a college class for one semester, the report detailed.

Von Ahn said: "If you ask people why they play Duolingo, some people tell you it's because they really want to learn a language, but the most common answer is that it's fun but they aren't wasting their time. They're procrastinating, but they think about it as healthy food."

The Pennsylvania-based startup makes money mainly through its web version. The firm crowdsources translation pieces completed by its students and sells them to CNN, BuzzFeed, and other similar companies, the report said.

Duolingo will use the new capital to tap into the Asian market and tackle the fierce competition there. At present, the company is putting together 18 launguage programs through its community-based platform, Forbes reported.