Duolingo: Apple's choice for App of the Year

• Professor and student came up with app with learn languages
• The app is 100%25 free
• Six languages available for learning

LOS ANGELES — At Carnegie Mellon University where he teaches computer science, Luis von Ahn and student Severin Hacker thought there should be a way to use smartphones to teach new languages.

Sure, there was Rosetta Stone, but it's an expensive program (it starts at $274), and the folks who really need to learn to speak other languages "don't have the money," says von Ahn. "They need it to get a better job."

So they put their heads together and came up with Duolingo, which was released at the end of 2012. Twelve months later, Duolingo has seen 10 million downloads. And now Apple has deemed it the free iPhone App of the Year. (The app is also available for Android.)

"We're super happy," says von Ahn, who still teaches but plans to take the next semester off to devote to Duolingo. "It came as a surprise to us."

Duolingo is still free, and offers six languages — Spanish, French, German, Italian, English and Portuguese.

Open the app, and it's like a game. It uses pictures, your smartphone's microphone and video clips to help you learn words, recite them and write them out as well.

There are now 30 people working at Duolingo, which is monetized via its website, where Duolingo users volunteer to help translate web pages for clients, which include CNN and BuzzFeed. Some 100 documents are translated each day.

For 2014, von Ahn wants to see many more languages added.

"We'd like to see 50 languages within the next months," he says.

But don't worry folks: The free app isn't going to start charging you in 2014.

"We're fundamentalists on the belief that we should not charge for language education."

For its iPad app of the year, Apple chose Disney Animated, the $9.99 behind-the-scenes tour of the Disney cartoon library, with original drawings and videos.