Free crowdsourced language learning site Duolingo, Inc. has raised $45 million Series D in a round led by Google Capital that included previous investors Union Square Ventures, New Enterprise Associates, Tim Ferris, Ashton Kutcher, and Kleiner Perkins Caufield & Byers.

According to reports, the round valued the company at $470 million.

Pittsburgh, PA-based Duolingo offers free language learning and crowdsourced text translation across a range of primarily European languages, including Latin American Spanish, French, German, Brazilian Portuguese, Italian, Dutch, Irish, Danish, Swedish, Turkish, Norwegian, Ukrainian, and for those mad enough to see a use for it, Esperanto.

The site also teaches American English to those who speak Spanish, French, German, Portuguese, Italian, Greek, Dutch, Russian, Polish, Turkish, Hungarian, Romanian, Japanese, Hindi, Indonesian, Korean, Vietnamese, and Czech.

Originally a Carnegie Mellon University project led by Professor Luis von Ahn (the creator of reCAPTCHA,) the company spun out of the University in 2011 and has grown to 100 million users, a surprising number given it’s not exactly a household name.

As well as offering its website, Duolingo also offers apps on iOS, Android, and Windows Phone, and well at that: the app sits at the top ranked position in the education category in both the Apple App Store and Google Play.

“Duolingo’s mobile­ first, adaptive, and gamified platform is changing the way people are learning languages across the globe,” Google Capital Partner Laela Sturdy said in a statement. “We were blown away by Duolingo’s growth and engagement numbers, and we’re thrilled to partner with them as they shape the future of education.”

Along with their consumer-facing side, the company also offers a platform for teachers called Duolingo for Schools that offers a blended learning companion for their classrooms. The service offers lesson plans, allows teachers to assign homework, along with gameplay to encourage learning.

Duolingo for Schools is said to already have 100,000 teachers globally using the service.

Monetization

The one thing that stood out from the funding round was a complete and utter lack of any mention as to how Duolingo makes money, while there are plenty of mentions about all the free things they give away.

The company is previously said to work with CNN for paid translations, and charge for certified testing, but that seems to be the extent of it.

It’s hard not to like the service, be it that it’s grossly Eurocentric, but startups taking piles of venture capital really need to look past the kumbaya altruistic stuff and consider that the money doesn’t last forever, and they do actually need at some stage to focus on making some from the product or service they’re offering.

Including the new round, Duolingo has raised $83.3 million to-date. All previous investors participated in the new round.