Duolingo, the developer behind the popular language-learning app of the same name, has raised another $20 million in funding.

The Series C round was led by Kleiner Perkins and brings Duolingo's total funding to date to $38 million. The plan, according to founder Luis von Ahn, is to use the additional funds to ramp up hiring and improve its existing product to include more analytics, language options and the ability to get certified in a new language.

"We are already the largest way to learn languages online," von Ahn says. "The goal now is to just completely dominate and I think that we can do that, but for that we need to expand into more languages and add a lot more features."

Duolingo launched its website in mid-2012 and its app a few months later. The app has been praised by a number of publications for its unique model of gamifying the process of learning a new language.

Von Ahn says Duolingo now has 25 million users, helped in part by the fact that the app has been promoted in both the Apple App Store and Google Play. Duolingo is currently adding about 100,000 new users a day.

Though the focus for 2014 is to continue building out the language app, von Ahn says the company may expand to other education services sometime in 2015.

"We may start going to other types of education because our apps have been so successful in education," he says. "We've considered all kinds of things: math, programming, etc. We don't have a specific category we would go to."