Duolingo also offers the Duolingo English Test, an online language assessment, and Duolingo ABC, a literacy app designed for children. The company follows a freemium model, with optional premium services like Super Duolingo and Duolingo Max, which are ad-free and provide additional features. Additionally, Duolingo runs Duo's Taqueria, a Mexican taco restaurant in Pittsburgh.
With over 130 million monthly active users, Duolingo is the most popular educational app in the world.[10][11][12] Over 10 million people have a Duolingo streak longer than a year.[13] In total, learners on Duolingo complete more than 13 billion exercises per week.[14] A systematic review of research on Duolingo from 2012 to 2020 found comparatively few studies on the platform's efficiency for language learning but identified several studies that reported relatively high user satisfaction, enjoyment, and positive perceptions of the app's effectiveness.[15] The company has also been recognized for its successful marketing tactics and strong brand engagement.[16][17]
History
Early history
The idea of Duolingo was formulated in 2009 by Carnegie Mellon University professor Luis von Ahn and his Swiss-born post-graduate student Severin Hacker.[18][19] Von Ahn had sold his second company, reCAPTCHA, to Google and, with Hacker, wanted to work on an education-related project.[20] Von Ahn stated that he saw how expensive it was for people in his community in Guatemala to learn English.[21][22] Hacker (co-founder and current CTO of Duolingo) believed that "free education will really change the world"[23] and wanted to provide an accessible means for doing so. He was recognized by the National Inventors Hall of Fame for his contributions to language learning and technological development.[24] The Duo mascot is a green owl because co-founder Severin Hacker hates the color green.[25]
In October 2011, Duolingo announced that it had raised $3.3 million from a Series A round of funding, led by Union Square Ventures, with participation from author Tim Ferriss and actor Ashton Kutcher's investing firm A-Grade Investments.[31] Duolingo launched a private beta on November 30, 2011, and accumulated a waiting list of more than 100,000 people by December 13.[32][33] It launched to the general public on June 19, 2012, at which point the waiting list had grown to around 500,000.[34][35]
In September 2012, Duolingo announced that it had raised a further $15 million from a Series B funding round led by New Enterprise Associates, with participation from Union Square Ventures.[36] In November 2012, Duolingo released an iPhone app,[37] followed by an Android app in May 2013, at which time Duolingo had around 3 million users.[38] By July 2013, it had grown to 5 million users and was rated the No. 1 free education app in the Google Play Store.[39]
In February 2014, Duolingo announced that it had raised $20 million from a Series C funding round led by Kleiner Caufield & Byers, with prior investors also participating.[40] At this time, it had 34 employees, and reported about 25 million registered users and 12.5 million active users;[40] it later reported a figure closer to 60 million users.[41]
In June 2015, Duolingo announced that it had raised $45 million from a Series D funding round led by Google Capital, bringing its total funding to $83.3 million. The round valued the company at around $470 million, with 100 million registered users globally.[29][41] In April 2016, it was reported that Duolingo had more than 18 million monthly users.[42][43]
In July 2017, Duolingo announced that it had raised $25 million in a Series E funding round led by Drive Capital, bringing its total funding to $108.3 million. The round valued Duolingo at $700 million, and the company reported passing 200 million registered users, with 25 million active users.[44] It was reported that Duolingo had 95 employees.[45] Funds from the Series E round would be directed toward creating initiatives such as a related educational flashcard app, TinyCards, and testbeds for initiatives related to reading and listening comprehension.[46] On August 1, 2018, Duolingo surpassed 300 million registered users.[47]
In December 2019, it was announced that Duolingo raised $30 million in a Series F funding round from Alphabet's investment company, CapitalG.[22] The round valued Duolingo at $1.5 billion. Duolingo reported 30 million active users at this time. The headcount at the company had increased to around two hundred, and new offices had been opened in Seattle, New York, and Beijing.[48] Duolingo planned to use the funds to develop new products and further expand its team in sectors like engineering, business development, design, curriculum and content creators, community outreach, and marketing.[49]
Features and media
Duolingo in 2017
In October 2013, Duolingo launched a crowdsourced language incubator.[50] In March 2021, it announced that it would be ending its volunteer contributor program. The company said that language courses would instead be maintained and developed by professional linguists aligning with CEFR standards.[51][non-primary source needed] On June 28, 2021, Duolingo filed for an initial public offering on NASDAQ under the ticker DUOL.[52] From August 2021 to June 2022, the Duolingo language learning app was removed from some app stores in China.[53]
In August 2022, Duolingo overhauled its interface, changing its course structure from a tree-like design, where users could choose from a range of lessons after completing previous ones, to a linear progression. This update has been criticized by users across social media outlets, such as Reddit and Twitter.[21] CEO Luis von Ahn stated that there were no plans to reverse the changes.[54] In October 2022, Duolingo acquired Detroit-based animation studio Gunner; it is the studio that produces art assets and animation for Duolingo and Duolingo ABC and its marketing campaigns.[citation needed]
In March 2023, Duolingo officially announced the planned Duolingo Max, a subscription tier above Super Duolingo, in their blog.[55] In October 2023, Duolingo released math and music courses in English and Spanish for iOS users.[56][57]
In January 2024, Duolingo fired some contractors and announced plans to replace them with AI.[58][59] The company acquired Detroit-based design studio Hobbes in March.[60]
As of 2014, most of Duolingo's language learning features are free with advertising. Users can remove advertising by paying a subscription fee or promoting referral links.[62] The paid user program, Super Duolingo (formerly known as Duolingo Plus), offers unlimited retries and access to some additional types of lessons. It is otherwise identical to Duolingo for Schools.[63][64][non-primary source needed]
Duolingo Max
Duolingo Max is a subscription above Super Duolingo that adds additional functions using generative AI: Roleplay, an AI conversation partner; Explain My Answer, which breaks down the rules with a modified GPT-4 when the user makes a mistake; and Video Call, where users can have video chat with one of the characters, which currently only includes Lily. Intended to provide immersion through conversation.[65][non-primary source needed]
Duolingo for Schools
Duolingo for Schools is designed to help teachers use Duolingo in their classrooms. It allows teachers to create classrooms, assign lessons, track student progress, and personalize learning.[66][non-primary source needed]
The Duolingo English Test (DET) is an online English proficiency test that measures proficiency in reading, writing, speaking, and listening in English. It is a computer-based test scored on a scale of 10–160, with scores above 120 considered English proficiency. The test's questions algorithmically adjust to the test-takers' ability level. The test's certificate is reportedly accepted by over 5,500 programs internationally,[67] albeit with exceptions.[68]
Other programs
Duolingo Math is an app course for learning elementary mathematics. It was announced on YouTube on August 27, 2022.[69]
On October 11, 2023, the company released Duolingo Music,[57] a new platform within the existing app that provides basic music learning through piano and sheet music lessons.[70][71]
Duolingo introduced chess lessons in beta in April 2025, with an initial rollout planned for iOS in English by May. The lessons are structured around the Elo rating system, gradually increasing in difficulty to match the user's skill level. Learners can play mini-matches or full games against Duolingo’s virtual chess coach, Oscar, whose difficulty also scales with progress. At launch, users are not able to play against each other.[72][73]
Duolingo ABC is a free app designed for young children to learn letters, their sounds, phonics, and other early reading concepts. Released in 2020, it does not contain ads or in-app purchases. As of April 2024, iOS and Android versions are available, but only in English.[8][74]
Learning model
Exercises and pacing
On Duolingo, learners learn by doing, engaging with the course material.[75] Lessons are designed to be brief, allowing users to learn in manageable chunks.[76][77] Duolingo uses a gamified approach to learning, with lessons that incorporate translating, interactive exercises, quizzes, and stories.[78] It also uses an algorithm that adapts to each learner and can provide personalized feedback and recommendations.
Gamification
Duolingo provides a competitive space,[79] such as in leagues, where people can compete with randomly selected worldwide player groupings of up to 30 users. Leagues: Bronze, Silver, Gold, Sapphire, Ruby, Emerald, Amethyst, Pearl, Obsidian, Diamond. Rankings in leagues are determined by the number of experience points earned in a week. Badges in Duolingo represent achievements earned from completing specific objectives.[80] Users can also create their own avatars.[81][82]
Any lesson completed in Duolingo will count towards the user's daily streak.[83] The daily streak's visual symbol in the app is fire. Duolingo's "Friend Streak" lets users maintain streaks with up to five friends.[84] Streaks encourage consistent daily practice and help build a habit of regular learning.
The app has a personalized bandit algorithm system (later the A/B tested variant recovering difference softmax algorithm) that determines the daily notification that will be sent out to the user.[85]
Duolingo Score
The Duolingo Score is an estimate of users’ proficiency in the language they're learning in CEFR-aligned courses. Duolingo Score provides a granular assessment of what a student has learned and they can do with the language.[86]DET is using a similar scoring system. The most developed CEFR-aligned courses (French, English and Spanish) cover Duolingo Score from 0 to 130.
Duolingo Score
CEFR level
Student can...
0–9
very early A1
use simple words and phrases in some common scenarios
10–19
early A1
talk about themselves and where they live and ask and answer simple questions
20–29
high A1
discuss their daily routine, order food at a restaurant, and chat a little
30–59
A2
have basic conversations about familiar topics, including weather, shopping, hobbies, and holiday plans
60–79
early B1
handle common situations while traveling, ask for directions, and make reservations
80–99
high B1
share their opinion, tell stories, and navigate most daily situations
100–114
early B2
have deep discussions about their interests and understand news, movies, and jokes
115–129
high B2
express themselves in most situations and uses the language in professional and academic scenarios
130–160
C1 and C2
easily understand all that they hear or read and expresses nuanced thoughts in sophisticated language
Business model
Duolingo operates on a freemium business model, offering free access to its learning platforms with ads. Revenue is primarily generated through subscriptions, which remove ads, and provide other perks like unlimited hearts and generative AI. The app also generates income from in-app purchases of virtual currency (Gems) and power-ups that enhance the learning experience. Another key revenue stream is the Duolingo English Test (DET), a low-cost English proficiency test.[87]
In April 2020, it passed one million paid subscribers;[88] it reached 2.9 million in March 2022,[89] and 4.8 million at the end of March 2023.[90] As of June 2024 Duolingo has 8 million paying subscribers.
Duolingo had revenue of $531 million in 2023, compared to $250.77 million in 2021,[91] $36 million in 2018,[92] $13 million in 2017,[47] and $1 million in 2016. In May 2022, it was reported that 6.8% of its monthly active users paid for the ad-free version of the app.[93]
Reception
Effectiveness
A 2017 study found no significant difference between elementary students learning Spanish through the "gamification" of the Duolingo app and those learning in classroom environments, with both groups demonstrating a similar increase in achievements and self-efficacy.[94]
Duolingo's occasional use of 'erratic' phrases—such as "The bride is a woman and the groom is a hedgehog" or "The man eats ice cream with mustard"[95]—is reportedly derived from research published in 2018 by psychologists at Ghent University in Belgium,[96] which concluded that such "semantically unpredictable sentences" were more effective for language learning than conventional and predictable phrases, based on the concept of "reward prediction errors", in which unexpected or surprising outcomes are more rewarding and thus encourage further learning.[97][95]
A 2022 study on adults using Duolingo as their only language learning tool, published in the journal Foreign Language Annals, found that participants who completed a course had similar reading and listening proficiency to university students after four semesters of study, concluding that Duolingo could be an effective tool for language learning.[98] Another 2022 study of Malaysian students learning French, published by the National University of Malaysia Press, found that the app facilitated the acquisition of vocabulary and concluded that it was "well suited" for beginners in this regard.[99]
According to Duolingo's own 2021 study, five sections of the app are roughly equivalent to five semesters of university instruction, and Duolingo is an "effective tool [...] at an intermediate level".[100][101] A 2023 study funded by Duolingo concluded that Duolingo English learners did not significantly learn much grammar.[102] Duolingo English learners in Colombia and Spain were found to gain significantly more proficiency than students in a classroom, except for listening.[103]
Criticism
Some language professionals have criticized the app for its limitations and gamified design.[104] Players have also reported that "gamification" has led to cheating, hacking, and incentivized game strategies that conflict with actual learning.[105]
In March 2022, Duolingo forums were discontinued,[106] and sentence discussions became read-only.[107] The change has been criticized on some social media sites.
In January 2023, Duolingo's data on over 2.6 million users' usernames, names, and phone numbers was sold in a hacker forum. Duolingo later stated that they would investigate the "dark web post".[108] They concluded that the data was obtained by scraping publicly available information based on an exposed application programming interface (API).[109][110] Duolingo's spokesperson states that the API is intentionally publicly visible.
Since the end of October 2023, Duolingo has stopped updating its Welsh course to "focus on languages in higher demand". Some users criticized this decision because it came at the expense of learners of a language with limited resources on the market and the potential halting of the Welsh Government's "Cymraeg 2050" strategy to promote Welsh language learning.[111][112]
Duolingo courses vary greatly in quality. While most popular language courses like Spanish or French are well developed, other courses for less studied languages like Ukrainian cover very little grammar and vocabulary.[113][114]
In 2025, CEO Luis von Ahn announced Duolingo would become an "AI-first" company and would be replacing contracted workers with artificial intelligence through automation.[115][116] This decision was met with public outcry, leading many users declaring they have ended their learning streaks in protest.[117]
Awards
In 2013, Apple chose Duolingo as its iPhone App of the Year, a first for an educational application.[118] That year, Duolingo ranked No.7 on Fast Company's "The World's Most Innovative Companies: Education Honorees" list "for crowdsourcing web translation by turning it into a free language-learning program".[119][120][121] Duolingo won Best Education Startup at the 2014 Crunchies,[122][123] and was the most downloaded 'education app' in Google Play in 2013 and 2014.[124] In July 2020, PCMag named it "The Best Free Language Learning App".[125]
As a company, Duolingo has likewise won several awards and recognitions. In 2015, it was announced as that year's Index Award winner in the Play & Learning category by The Index Project.[126] It won Inc. magazine's Best Workplaces 2018,[127] made Entrepreneur magazine's Top Company Culture List 2018,[128] was among CNBC's "Disruptor 50" lists for 2018 and 2019,[129][130][131] and was ranked as one of TIME magazine's 50 Genius Companies.[132] Duolingo was named one of Forbes's "Next Billion-Dollar Startups 2019".[133] In 2023, Duolingo won a Design Award during the 2023 edition of the Apple Design Awards.[134]
Beatrice "Bea" Boateng:[138] Born on January 1, 2000,[138] Bea is a smart and energetic young girl.
Duo Keyshauna Renee Lingo: Commonly known as Duo or Duo the Owl, he is the company's green owl mascot. On February 11, 2025, Duolingo announced, as part of a publicity stunt, that Duo had died,[139][140][141] after being hit by a Tesla Cybertruck.[142][143][144] Later, Duolingo put up a website where the users of the app would have to work together to obtain 50 Billion in-app experience to resurrect Duo.[145] After the goal was reached, Duolingo then posted a video on their social medias of Duo's resurrection.[146] The company also stated the character's birth date as 1000BC, and his full name as Duo Keyshauna Renee Lingo.[147][148] Duo served as the motivational face of the app, encouraging users to complete their lessons and maintain their learning streaks. Duo has become a well-known internet character, often depicted humorously as aggressively reminding users to not miss their streaks. Over time, Duo has gained a significant reputation in memes for being persistent—even threatening—about keeping users on track with their lessons. According to Duolingo Brand Guidelines, "Duo is a boy" and communicates through text only.[149]
Eddy: An optimistic character with a passion for sports, father of Junior.
Falstaff: An older, intellectual grizzly bear with a love for literature.
Junior: A curious and eager young boy.
Lily: A teenage girl known for her sarcastic, emo, and indifferent personality, often expressing a lack of enthusiasm but secretly caring about her friends. She is one of the main characters in Duolingo’s cast of mascots used in video call feature.[150]
Lin: A creative and adventurous artist and motorcyclist.
Lucy: A venturesome elderly lady, grandmother of Lin.
Oscar: A high school teacher and a prim connoisseur of art and culture.
Vikram: A calm and responsible professional.
Zari: A confident and enthusiastic Middle Eastern teenage girl. She dresses in pink and blue and wears a headscarf/hijab. She is Lily's best friend.
All characters mentioned above are human, with the exceptions of Duo, who is an owl, and Falstaff, who is a bear.
In popular culture
Due to the app's frequent reminder notifications, Duolingo's mascot, a green cartoon owl named Duo, has been the subject of Internet memes antagonising him, with the character often depicted stalking or threatening users if they do not continue using the app.[151][152]
Duolingo has leaned into its online reputation and has adjusted its social media and marketing strategies accordingly.[153] Acknowledging the meme, Duolingo released a video on April Fools' Day 2019, depicting a facetious new feature called "Duolingo Push". In the video, users of "Duolingo Push" are reminded to use the app by Duo himself (depicted by a person wearing a Duolingo mascot costume), who stares at and follows them until they comply.[154][155] It was also acknowledged during Duolingo's 2022 April Fools' Day video, "Lawyer Fights Duolingo Owl for $2,700,000", where a fictitious law firm fights for those that have been harmed by Duolingo's owl mascot.[156] This was further referenced by the company in its 2024 April Fools' Day skit "Duo on Ice", in which the owl, in a mix of Spanish and English, admitted to having an appetite for human flesh, and if the user failed to continue their streak, they would "eat their head like a praying mantis."[157] In February 2020, as part of the company's partnership with the developers of the video game Angry Birds 2, a skit depicting Duo and the red Angry Bird attacking a crowd was uploaded.[158]
Duolingo has effectively engaged with Generation Alpha through its YouTube shorts, featuring global meme trends and content like songs, workplace insights, and humor, including elements of dark comedy, and "kidnapping children" as a joke.[159]
In November 2019, Saturday Night Live parodied Duolingo in a sketch where adults learned to communicate with children by using a fictitious course called "Duolingo for Talking to Children".[160]
The 2023 film Barbie contains a running gag where the husband of disgruntled Mattel employee Gloria uses Duolingo to learn Spanish, Gloria's native language.
Duo's Taqueria
Duo's Taqueria is a taqueria (a Mexican taco restaurant) in Pittsburgh, Pennsylvania, operated by Duolingo. The taqueria offers a variety of authentic Mexican tacos and other traditional dishes.[161] The restaurant encourages patrons to order in Spanish, aligning with Duolingo's mission of making language learning fun and accessible. Duolingo's taco shop brought in $700,000 in 2023.[162]
In 2024, Duolingo opened a new office in New York City, featuring an art gallery in which the company's characters are depicted in the style of famous historical paintings. The gallery showcases moving images of Duo and other characters in a range of artistic styles.[166][167]
^Huynh, Duy; Zuo, Long; Iida, Hiroyuki (2016). "Analyzing Gamification of "Duolingo" with Focus on its Course Structure". Games and Learning Alliance. Lecture Notes in Computer Science. Vol. 10056. Springer, Cham. pp. 268–277. doi:10.1007/978-3-319-50182-6_24. ISBN978-3319501819.
^Duolingo Path (September 7, 2024). Duolingo Clash. Retrieved September 8, 2024 – via YouTube.
^Rachels, Jason R.; Rockinson-Szapkiw, Amanda J. (2018). "The effects of a mobile gamification app on elementary students' Spanish achievement and self-efficacy". Computer Assisted Language Learning. 31 (1–2). Routledge: 72–89. doi:10.1080/09588221.2017.1382536. S2CID67064098.
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