The app, which has around 300 million users worldwide, also administers its own English language test that is already accepted in over 300 college-level schools.

With 32.7 million Duolingo users, Brazil can be an important market for this strategy, says Luis von Ahn, Duolingo's co-founder and CEO. The country is the second largest market in user numbers, right behind the United States. Ahn says:

I believe that in two or three years most American universities will accept Duolingo's certification. We are already in 10% of them and we gain two or three more every week.

Duolingo plans to take on the TOEFL by stressing the more affordable price of its exam and a higher degree of convenience.

Check out: How to Self-Prepare for English Tests

While the TOEFL costs USD 215 and requires scheduling in testing centers, Duolingo's English as a Second Language test costs just USD 50 and can be done anytime, anywhere on a personal computer. The only demand is that the user keep his computer camera on so Duolingo's checkers can make sure the test was taken by a real person before issuing the scores.

Duolingo's test is just 30 minutes long, much shorter than traditional tests which can take up to four hours to complete.

Smartphone apps like Duolingo that help people learn languages for free or nearly free have been piling pressure on established education firms over the last years. A great number of users are being drawn to the flexibility of practicing vocabulary or conversation on the go, either as part of a serious course of study or simply as a more productive alternative to casual video gaming.

Check out: Show Your English Proficiency with TOEFL iBT

Pittsburgh-based Duolingo is the top language app globally in terms of users. Last year, the company announced it had attracted USD 108.3 million in financing and reached a valuation of USD 700 million.

Source: Folha de S.Paulo, Reuters