[Techtaffy Newsdesk]

Duolingo, a free language learning service co-founded by one of the inventors of CAPTCHA, has raised a $15M Series B round. The financing was led by New Enterprise Associates (NEA), with participation from existing investor Union Square Ventures.  Harry Weller from NEA is joining the company’s board.

Since its public launch in June 2012, Duolingo’s user community has grown to more than 250,000 active language learners, says the company. Duolingo’s expanded offerings now include English, Spanish, French, German, and Portuguese. Italian and Chinese will be offered later this year, and an iPhone app is in the works as well.

Dr. Luis von Ahn: We’ll use the funds to continue improving Duolingo and to add way more languages :)

Dr. Luis von Ahn, a computer science professor at Carnegie Mellon University, co-founded Duolingo with his PhD student Severin Hacker in 2011. Dr. von Ahn is also co-inventor of the popular CAPTCHA and founder of the ESP Game (now Google Image Labeler, acquired by Google in 2004) and reCAPTCHA (acquired by Google in 2009).

Duolingo is an online social platform that teaches users a new language while they simultaneously translate content across the Web.