Language learning platform Duolingo Inc. announced today that it has closed a $25 million late-stage funding round led by Drive Capital.

According to the company, the Series E round brings its total funding to $108.3 million and sets its overall valuation at $700 million.

Founded in 2011 by reCAPTCHA co-creator Luis von Ahn (pictured), Duolingo’s platform offers beginner and moderate-level language courses for more than two dozen languages, including Spanish, French, German, Russian and Japanese. The site even offers courses in invented languages such as Esperanto, as well as fictional languages such as Klingon from Star Trek and High Valyrian from Game of Thrones.

Rather than feeding vocabulary and grammar to users, Duolingo uses gamelike exercises that to teach language skills. The service is free with ads, but users can opt to pay for an ad-free premium version. Duolingo also offers a separate platform for schools that allows teachers to create lesson plans and track student progress.

Duolingo’s app has rapidly grown in popularity over the last few years, and it now boasts more than 200 million users. The company said its app is the most popular language learning platform and the most downloaded education app in the world.

“When we started Duolingo five years ago we set out to make language learning free and accessible for everyone in the world,” Ahn said in a statement. “At the time, we thought it would be pretty cool if we could reach one million users. Our growth since then has significantly surpassed those initial expectations, and this funding will help us bring free education to millions more as we build a sustainable and profitable business.”

In addition to its continued focus on user growth, Duolingo says it will also use its new funding to further develop its app as well as new products, such as its flashcard app, Tinycards, and its English certification exam, the Duolingo English Test. The company has also started experimenting with new technology like AI chatbots, and it plans to nearly double its staff by the end of 2018.

Photo: Duolingo