40 Fun Facts About Duolingo

Duolingo's owl mascot Duo is which color, chosen as a joke because one co-founder disliked it so much?

Green was co-founder Severin Hacker's least favorite color, so Luis von Ahn chose it for the mascot just to tease him.

In a 2025 publicity stunt, Duolingo announced that its owl mascot Duo had been killed by which vehicle?

A Tesla Cybertruck was named as the culprit, and Duo was brought back only after learners around the world earned 50 billion XP together.

What food is sold at the restaurant Duolingo runs beside its headquarters, where diners are urged to order in Spanish?

Tacos are the specialty at Duo's Taqueria, a stand next to the company's offices that brought in $700,000 in 2023.

Before Duolingo, Luis von Ahn helped pioneer which everyday web annoyance, later reworked to help digitize old books?

CAPTCHA tests were eating up millions of hours of human effort, so von Ahn's follow-up version put that typing to work deciphering words that scanners could not read.

Duolingo boss Luis von Ahn grew up in which Central American country, where he saw how costly learning English was?

Guatemala City is where von Ahn was born and raised by a single mother, who was one of the first women in the country to finish medical school.

Which Hollywood actor's firm A-Grade Investments backed Duolingo in 2011, before the app had opened to the public?

Ashton Kutcher's firm joined a $3.3 million round led by Union Square Ventures, months before the public launch in June 2012.

Which American comedy show parodied Duolingo in 2019 with a sketch about a made-up course?

Saturday Night Live imagined a course for adults who needed lessons in how to talk to children.

Duolingo teaches High Valyrian, a language David J. Peterson invented for which hit fantasy television series?

Game of Thrones needed working languages, and Peterson later helped build the Duolingo course, expanding it when House of the Dragon premiered.

Which Star Trek language has a Duolingo course whose unusual capital letters and apostrophes caused software problems?

Klingon treats the apostrophe as a consonant and mixes upper- and lower-case letters in unexpected ways, quirks that kept the course in beta while the bugs were fixed.

Which jewel names the highest of the ten weekly leagues that Duolingo learners climb by earning XP?

Diamond became the summit when the leaderboards grew from five leagues to ten, and its top ten finishers can enter a knockout tournament.

Duolingo has its headquarters in which American city, where its two founders met at university?

Pittsburgh is home to Carnegie Mellon University, where the idea for the app took shape in 2009 between a professor and his graduate student.

Severin Hacker, the Duolingo co-founder and chief technology officer, was born and raised in which European country?

Switzerland is where Hacker grew up, in the town of Zug, and he has said an obsession with video games first drew him to computers.

Duolingo was first financed partly by which award, often nicknamed a genius grant, that Luis von Ahn won in 2006?

A MacArthur fellowship and a National Science Foundation grant paid for the early work, and the founders even considered running Duolingo as a nonprofit.

Which technology company named Duolingo its App of the Year in 2013, a year after the public launch?

Apple gave Duolingo its iPhone App of the Year title, and the app was also the most downloaded education app on Google Play that year.

Duolingo shares began trading in 2021 under the ticker DUOL on which stock exchange?

Nasdaq was the exchange named when the company filed to go public in June 2021, about a decade after it raised its first venture money.

Which symbols, one lost for each mistake, did Duolingo begin replacing with a pink Energy battery in 2025?

Hearts were dropped because beginners were twice as likely to run out of them mid-lesson, which the company found discouraging.

What is the name of Duolingo's in-app currency, which learners can spend in the Shop on a Streak Freeze?

Gems can also buy timer boosts and Energy refills, and selling them is one of the ways the free app makes money.

Which symbol sits beside a Duolingo learner's streak, the count of days in a row they have studied?

A flame marks the streak, which grows by one with each day's lesson and can be shared with up to five friends as a Friend Streak.

What does XP stand for in Duolingo, where weekly XP totals decide who moves up to the next league?

Experience points are earned for finishing lessons, stories and timed challenges, with bonuses on offer at certain times of day.

Before a contested 2022 redesign put every lesson on one linear path, Duolingo courses were laid out like what?

A tree of branching skills let learners choose among several lessons; its removal drew complaints, but Luis von Ahn said the change would not be reversed.

Until 2021, many Duolingo courses were built in its Incubator by which group, since replaced by professional linguists?

Volunteers built courses through a crowdsourced incubator that opened in October 2013, a scheme the company wound down in March 2021.

Luis von Ahn once had to fly to El Salvador to sit which admissions exam, souring him on the testing industry?

TOEFL was required for his American college applications and the trip cost more than $1,200; his company later launched a low-cost online English test of its own.

Which 1980s home computer, a gift to eight-year-old Luis von Ahn, sparked the Duolingo founder's love of technology?

Commodore 64 computers were his mother's choice of present, and the gift set him on a path to a computer science doctorate from Carnegie Mellon in 2005.

Before ads and subscriptions, Duolingo planned to make money by having learners do which task while they practiced?

Translating web pages was the original idea: von Ahn asked how 100 million people could turn the internet into every language for free.

Before a 2022 rebrand to Super Duolingo, the app's paid ad-free subscription carried which word after the brand name?

Plus was judged too predictable a label, so the company took Super from video games, anime and comic books, where it marks the bigger, better version.

Duolingo Max, a pricier subscription tier launched in 2023 with chatbot role-plays, was built on which OpenAI model?

GPT-4 was OpenAI's newest model at the time, and Duolingo spent months testing it with the lab before launching features such as Roleplay.

What kind of animal is Falstaff, the gruff but helpful Duolingo character who coaches learners through video calls?

A bear with a gruff exterior, Falstaff leads guided calls by asking questions, suggesting phrases and giving feedback in the learner's own language.

Which Duolingo character, an introvert known for her sarcasm, is the best friend of outgoing overachiever Zari?

Lily is said by her creators to listen only to bands nobody has heard of, and the cast pairs opposites on purpose because clashing personalities make better stories.

Duolingo drew criticism in 2023 when it stopped updating its course in which Celtic language?

Welsh learners feared the freeze would hurt the government's Cymraeg 2050 strategy to promote the language; the company said it was focusing on languages in higher demand.

Which Native American language joined Duolingo in 2018, five years after the 1977 film Star Wars was dubbed into it?

Navajo had already made broadcasting history in 1996, when it became the first Native American language to carry a Super Bowl.

Which constructed language, devised in the 1880s as a universal second tongue, gained a free Duolingo course in 2015?

Esperanto had drawn 350,000 learners by the time the course left beta in 2016, and the total passed 1.3 million within two more years.

Which board game did Duolingo begin teaching in 2025, later adding a way for learners to play each other?

Chess joined math and music as the app's third subject beyond languages, with lessons that grow steadily harder.

Duolingo's music course, added to the app in October 2023, teaches sheet music through which on-screen instrument?

Piano lessons came first, and the company later bought the London start-up NextBeat to expand its music teaching.

From August 2021 to June 2022, the Duolingo app vanished from some app stores in which country?

China is also home to a Duolingo office in Beijing, which had opened by 2019, well before the app was pulled.

In 2025 Luis von Ahn sparked a backlash by announcing that Duolingo would become what kind of company?

AI-first meant gradually replacing contractors with automation, and angry users ended long streaks in protest while the company pulled its TikTok and Instagram videos.

Duolingo timed which kind of reminder to reach four million learners just as its 2024 Super Bowl ad aired?

A push notification landed within seconds of the five-second ad, which was made in-house, and engineers had to rebuild their sending system to manage it.

Which metal names the lowest of Duolingo's weekly leagues, where learners begin their climb up the leaderboards?

Bronze sits nine rungs from the top, below Silver, Gold and then a run of leagues named after jewels and stones.

Which self-help author, whose book Tools of Titans includes advice from Luis von Ahn, invested early in Duolingo?

Tim Ferriss took part in the $3.3 million round of October 2011, when the app was still weeks away from its private beta.

Luis von Ahn left home at 18 to study mathematics at which American university, graduating with top honors in 2000?

Duke awarded him a mathematics degree summa cum laude, and five years later he had a computer science doctorate from Carnegie Mellon.

On which comics platform did Duolingo launch Duo Unleashed, a 2024 series starring the app's cast of characters?

Webtoon hosted the first series and then a 2026 follow-up, Duo Leveling.