Luis von Ahn is a Guatemalan entrepreneur and an associate professor in the Computer Science Department at Carnegie Mellon University. He founded reCAPTCHA, which was sold to Google in 2009, and then co-founded Duolingo, world's largest language-learning online platform.

Duolingo was started as a project in Pittsburgh by von Ahn and his graduate student, Severin Hacker. Duolingo's effectiveness is due to its use of machine-learning algorithms that understand users' learning patterns to create personalized lessons, as well as rigorous big data analysis of its millions of users. It's free, with no ads. The service was designed to feel like a game that makes it effective — an independent study by City University of New York has shown that 34 hours on Duolingo are equivalent to a university semester of language classes.

I met Luis some time ago when he travelled to India, and talked about Duolingo's success and partnerships, the next set of goals, and why India is the market the company was focusing on right now. To coincide with the visit, the company announced the launch of the app in Hindi with a customized experience for Hindi speakers.

By the numbers

Duolingo has a total of 110 million users across the world. About 60 percent of Duolingo users use it for learning English.

In India, Duolingo has had a million app downloads with over 200,000 monthly active users. The growth is staggering since the number was 150,000 a month ago.


Duolingo is used for language education in many schools in United States. Five percent of all public schools in the U.S. use Duolingo to teach languages. We've also partnered with the government of Columbia, Mexico, and a few other countries. The UK, too.

We definitely want to partner with some schools in India. It makes a lot of sense to partner with schools in rural areas, where the school teacher also doesn't speak English well, and they can use Duolingo to teach English. It helps getting students excited about learning because it's a game. It is also personalized for an individual... so the content, speed, and style is tailored for an individual.

Focus on India

The latest version of the app is tailored for the Indian market. In most countries, we just launch the app. We don't bother in looking in how the people are using it. But India is a big enough market and we decide to look into its usage and patterns.

So, India is the first market we've ever customized Duolingo for. We've never had a dedicated team at Duolingo for a specific market. Now we are doing things that are very particular of how people use the app in India

One of the stupid assumptions we made was that you don't need to learn English if your phone's language is English. In India, a lot of people have their phone set to English, but they don't know English well. We made the incorrect assumption, and didn't show English as a language to be learned. This has changed now.

Also, typing in Hindi is rare. People prefer not to type in Hindi, and in fact they prefer to type Hindi in Roman letters. We've removed the need to type in Hindi in the app.

We're also working really hard to make the bandwidth usage a lot smaller. We've drastically reduced the size of the app. The Android app, for example, used to be 20 MB, and it is now about 7MB. We're trying to reduce it even more. We realized that a lot of people don't have a lot of space on their phones. We are trying to reach phones with low memory, while consuming less bandwidth.

We've also customized the content to make it more appealing to Hindi speakers. Our names are the same names we use across the world, but now we have Indian names and characters.

Right now, we teach English from Hindi. We want to add more languages — the top most spoken ones. Like Marathi, Bengali, Telugu, and Tamil are the ones that we are looking at. We should have them within this year.

Duolingo Test Center

In developing markets like India, learning English is crucial to people's professional development and can double or triple their income potential. Duolingo has partnerships with governments, schools and companies around the world to improve language education, and is keen on establishing similar partnerships in India.

For people who already know English, a lot of it is casual learning. For those who are learning English, they usually are serious learners. They actually want to learn for business, or whatever it is. With Duolingo, you can learn from zero to high-intermediate. You cannot get to "perfect," but you can get to a point by learning on Duolingo … you can probably get a job at a hotel, for example. You can't probably give a lecture on philosophy. People who learn English usually take it very seriously.

For language certification, we have Duolingo Test Center. We only offer it for English at the moment. We know that it is the majority of people who are learning the language seriously.

(A lot of traditional institutes offer English language coaching, both for casual and serious learners)

Our goal is to go all the way. It's a little bit of both — tech and culture issue.

What's Next?

We are working on making Duolingo better for conversation. That's big for us this year. A chat bot with an artificial intelligence… that's what we are looking at now. You can basically have a conversation, and you could integrate it with WhatsApp or Facebook Messenger or whatever.

(This interview happened before Microsoft's and Facebook's announcements about bot frameworks)

We are the number one education app on Android and iOS devices in 200 countries in the world. There are about 30 missing. One of those is India. That's a big goal.

Another goal is making the Test Center the de-facto way to prove that you know English in the world. We're not there yet, but we'd like to be. We are working with 12 US universities to accept Test Center instead of TOEFL. We hope that within a few years, everyone will be taking Test Center to prove they know English.

(According to a study conducted by University of Pittsburgh, there is a substantial correlation between the scores from Duolingo Test Center and TOEFL iBT.)

At the moment, entire government of Columbia accepts Duolingo as official language certification. Mexico soon. We are also working with well-known companies like Uber, for example. In certain countries, they've launched UberEnglish where you can order an Uber that speaks English and the way they prove English proficiency is via Duolingo Test Center.

We'll also start teaching English to Hindi. A lot of people have asked us for that, particularly in the US. Learning the language of your parents and grandparents is a very common thing in the US.

(Gina Gotthilf, in the photograph above with Luis von Ahn, is the VP of Growth at Duolingo.)


We never do paid marketing. We've never done any paid marketing. We've got all our users through word-of-mouth, and by blogs. We've never reached out to any institutions or governments. They usually reach out to us, since they realize a lot of their students are using the app anyway. It's free, so that's a good start.

We've just had the first ever pre-install deal. Going ahead, on all Lumia devices, Duolingo will be pre-installed. Globally. For this one too, Microsoft asked us, rather than us reaching out to them. We've not done anything like that before because usually you have to pay, and have a commercial arrangement with the OEM. Microsoft did it for free, and we are very happy about it.

(Luis Von Ahn wanted to create a program that served two purposes in one, what he calls a "twofer." Duolingo did this by teaching its users a foreign language while having them translate simple phrases in documents.)

We've moved away from the translation business. Our main business model is the Test Center now... the English language certification. We still have a few customers like CNN, but we're not taking in any new customers. We've completely moved out.


Because we want to be an education company, and not a translation company. We realized that the more we worked on that business model, the more we turned into a translation company.

(Test Center for other languages)

English at the moment. Spanish and French in the next six months. The vast majority of the language wants English for certifying that they know a language.

For learning languages, English is the biggest. People do want to learn other languages, but for certifying that they know a language, English is by far the biggest. Humongous. For work, admission to universities, and more.

Other big markets

After India, it will be China. But we are first concentrating on India. They are very similar in terms of market size, but we're more interested in India right now. It's more accessible right now. We have millions of user in China, but the focus right now is India.

Also, there are a lot of users in China, but the penetration is low. For example, 4% of online population in Brazil uses Duolingo. While in China, the number is like 0.1% or something.


We don't not have a big presence in Africa. South Africa and Egypt are the two OK markets for us.

There are a few reasons for it. We don't support any of their languages, unless they speak French. I think we have done nothing... we've never visited. We have a small team, so we have to focus. Last year we were just 30 employees. We are now 60.

(A chicken and egg problem, really.)

I think they are behind India in terms of smartphone adoption. We could get working on offering Duolingo on feature phones, but we'll rather wait for smartphone penetration.