✦ Could you keep this streak going?

✦ Could you keep this streak going?
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Hi Quartz members,

There’s a hidden duality to Duolingo, the app known for gamifying language learning. Users may experience it as a diversion that, through micro-lessons starring sometimes aggressive and always quirky cartoon characters, helps them retain the vocabulary they picked up on their last trip to Barcelona or Kyoto. But beneath the jovial surface and pavlovian bells and whistles, the Pittsburgh-based company has serious ambitions.

Luis Von Ahn, co-founder and CEO, says he created the app in 2009 partially as a tool for social mobility. The computer scientist grew up among the privileged class in Guatemala—his mother was a physician—and saw first-hand how wealth connected people to education and opportunities. He wanted to create an educational tool that would be free.

(Subscriptions are the company’s main source of revenue. Users who keep using the app for free receive ads; advertising is the company’s second biggest moneymaker.)

Does wrapping a social mission in cutesy animation work? Apparently so. The app has attracted around 38 million monthly active users, according to the company, and not all of them sign up for trivial reasons. Duolingo has been used by economic migrants and refugees in Europe, for example, to learn the native language in their newly adopted homes. Now the company is expanding beyond languages: Duolingo ABC, which teaches kids to read, just launched, and a math class for kids is in development.

Duolingo is also serious about staying relevant for the long haul. Following an IPO this summer, the firm is now worth more than $6 billion. Von Ahn says he wants to keep running the company the same way he did before it went public, by allowing employees to prioritize the educational experience and keeping the lessons free, no matter what pressures he faces every quarter. His staff, including engineers who he says turned down better paying jobs at Google or Microsoft because they believed in Duolingo’s mission, are counting on the leader to live up to that promise.


1.8 billion: People around the world learning to speak a new tongue every year

$21 to $115 billion: Estimated size of global digital language learning market within four to six years

40: Languages taught on Duolingo, in more than 100 courses. (One language may be offered in several courses. For example, there’s a Spanish course for English speakers and one for Chinese speakers)

500 million: Number of exercises completed by Duolingo users globally every day

$7: Monthly cost of a Duolingo Plus subscription if you don’t want to see any ads

5%: Share of Duolingo’s 40 million monthly active users paying for a monthly subscription

3,197: Longest streak (consecutive days of practice) by a power user, according to a Duolingo spokesperson

5: New courses Duolingo said it would introduce in 2021: Zulu, Xhosa, Maori, Tagalog, and Haitian Creole

The backstory

Duolingo initially relied on scores of volunteers to design courses other than the big ones like English and French. According to the company, the only way it could afford to scale up quickly and continue adding languages was to invite experts to design classes for free. But some members of Duolingo’s own forums have criticized the company for using unpaid labor while receiving millions in investments from venture capital firms. Those who defend the practice, however, say creating a course was an opportunity for language lovers to build their own CV and contribute to the mission.

The volunteer contributor program was closed last spring, just before the company’s IPO. At the time, Duolingo gave former volunteers up to $100,000 as acknowledgement of their past work. “Some of these people live in developing countries where $100,000 was a ton of money,” Von Ahn tells Quartz. “We just thought it was the right thing to do.”

That one weird trick!

Lessons on Duolingo and other education apps leverage spaced repetition—a method for reviewing content at specific intervals depending on how new it is or how well you’re remembering something—because it helps us better retain information in the long term.

A brief history

2007: Luis Von Ahn, then a student at Carnegie Mellon University, co-invents the digital security tool CAPTCHA. He would later sell two companies, including reCAPTCHA, to Google.

2009: Von Ahn, by now a professor at Carnegie Mellon University, and one of his graduate students, Severin Hacker, start Duolingo as a side project.

Nov. 30, 2011: Duolingo launches in beta, offering four languages: English, Spanish, French and German. Around 300,000 people are already on the waiting list.

2015: The company abandons its original model, which had users translating content from BuzzFeed and CNN articles, and moves toward instructor-designed courses.

2019: Saturday Night Live airs a satirical ad for “Duolingo for talking to children,” starring Kristen Stewart. The fictional product teaches adults how to speak to kids “because their friends are starting to have them.”

2020: Between March 11 and April 30, after the WHO declares the coronavirus crisis a pandemic, 30 million new users sign up for Duolingo, a 67% increase over the same period in 2019. Duolingo also becomes cash-flow positive.

July 28, 2021: Duolingo ends its first day as a public company with a valuation of nearly $5 billion, after shares soared by 36%.

More than words can say: The politics of language apps


Crowdsourcing materials from hundreds of volunteers was a bold move for Duolingo in its early years. Inevitably, some oddball sentences still turn up in class lessons.

On the Reddit site “Shit Duolingo says,” people share some of the baffling sentences they’ve come across while ascending through the ranks of Duolingo’s language “trees,” a.k.a course levels. Some are bleak—“Falling off the stage the actor died”—and others feel surreal, like “There’s a horse in your apartment.”

But the company has also had to answer for some questionable phrases that have turned up on the app. In one case, two consecutive sentences appeared to racially profile Spanish speakers as undocumented immigrants. Another time, French class got frisky with exercise examples such as “She raises her shirt.”

Duolingo also has to be cautious about course content that would have real-world consequences. To protect its overseas staff, Von Ahn says, Duolingo keeps its curriculum respectful of local laws and cultures. In Russia, where an oppressive “gay propaganda” law was enacted in 2013, a male character wouldn’t talk about his husband as he might in the US “because we have contractors in Russia helping us with our course and they could actually go to jail for something like that,” says Von Ahn. In Arabic countries, the characters’ dialogues avoid the topic of alcohol.

On Aug. 6, Duolingo was unexpectedly pulled from Android app stores in China, but not because of its content—Beijing began cracking down on for-profit edtech platforms. The app has been downloaded more than 15 million times in China, where more than 50% of users are studying English. A spokesperson for the company said that it is working with Chinese regulators and expects to be back in app stores “in the near future.”

KEEP learning

Have a great end to your week,

—Lila MacLellan (sporadically tests her hiragana with Duolingo)

One 🗣️ Thing

Pop quiz!

In 2020, Spanish overtook French as the second most popular language to study on the site, behind English. Which of the following is the fastest-growing language on the app?

A. Chinese
B. Japanese
C. Turkish
D. Hindi
E. Korean

Although all of these languages make up the top five, the answer is D, Hindi.

Correction: This piece originally stated that advertising was Duolingo’s biggest source of revenue. In fact, subscriptions is the company’s main moneymaker; advertising is second.