Duolingo
Duolingo ( ) is an American educational technology company that produces learning apps and provides language certification. Duolingo offers courses on music, math and over 40 languages, from popular languages such as English, French, and Spanish to less commonly studied languages such as Welsh, Irish, and Swahili. Other services include the Duolingo English Test certification program; Duolingo ABC, a literacy app for children. The company uses a freemium model, with its optional premium service, Super Duolingo, being ad-free and offering more features. As of February 2023, Duolingo was the most popular language learning app in the world based on monthly downloads, with almost 13.4 million users downloading the app that month. A systematic review of research on Duolingo from 2012 to 2020 found comparatively few studies on the platform's efficacy for language learning, but identified several studies that had reported relatively high user satisfaction and enjoyment and positive perceptions of the app's effectiveness. Subsequent studies have concluded that Duolingo is effective for language learning and the acquisition of vocabulary. History 
The idea for Duolingo originated in 2009 by Carnegie Mellon University professor Luis von Ahn and his Swiss-born post-graduate student Severin Hacker. Von Ahn had sold his second company, reCAPTCHA, to Google and, with Hacker, wanted to work on a project related to education. A driving motivation was Von Ahn's upbringing in Guatemala, where he saw how expensive it was for people in his community to learn English. Hacker (co-founder and current CTO of Duolingo) believed that "free education will really change the world" and wanted to provide an accessible means for doing so. The project was originally sponsored by Von Ahn's MacArthur fellowship and a National Science Foundation grant. The founders considered creating Duolingo as a nonprofit organization, but Von Ahn judged this model unsustainable. An early revenue stream, a crowdsourced translation service, was replaced by a Duolingo English Test certification program, advertising, and subscription. 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. Duolingo launched a private beta on November 27, 2011, and accumulated a waiting list of more than 300,000 people. It launched to the general public on June 19, 2012, at which point the waiting list had grown to around 500,000. 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. In November 2012, Duolingo released an iPhone app, followed by an Android app in May 2013, at which time Duolingo had around 3 million users. By July 2013, it had grown to 5 million users and was rated the No. 1 free education app in the Google Play Store. 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. At this time, it had 34 employees, and reported about 25 million registered users and 12.5 million active users; it later reported a figure closer to 60 million users. In June 2015, it 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. In April 2016, it was reported that Duolingo had more than 18 million monthly users. 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. It was reported that Duolingo had 95 employees. 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. On August 1, 2018, Duolingo surpassed 300 million registered users. In December 2019, it was announced that Duolingo raised $30 million in a Series F funding round from Alphabet's investment company CapitalG. 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 200, and new offices had been opened in Seattle, New York and Beijing. 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. In October 2013, Duolingo launched a crowdsourced language incubator. In March 2021, it announced that it would be ending its volunteer contributor program and donating money to its volunteer contributors who helped develop it. The company said that from now on, language courses would be maintained and developed by professional linguists aligning with CEFR standards. On 28 June 2021, Duolingo filed for an initial public offering on NASDAQ under the ticker DUOL. From August 2021 to June 2022, the Duolingo language learning app was removed from some app stores in China. In the early 2020s, Duolingo was noted for its viral videos on the social media platform TikTok. 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 was widely criticized by users across a variety of social media outlets, including Reddit and Twitter. CEO Luis von Ahn stated there were no plans to reverse the changes, which were intended to simplify Duolingo for new users, and that maintaining both the old and new versions would be difficult. In October 2022, Duolingo acquired Detroit-based animation studio Gunner. Services

Duolingo 
Duolingo uses a gamified approach to language learning, with lessons that incorporate translating, interactive exercises, quizzes and stories to make learning more engaging and fun. It also uses a unique algorithm that adapts to each learner's level and learning style, providing personalised feedback and recommendations. For some languages, Duolingo offers podcasts for people at intermediate levels, consisting of stories usually told by native speakers from different parts of the world where the target language is spoken. They use simplified grammar and vocabulary and slower intonation and include occasional assistance with context and explanations of unusual words. Duolingo has been through many design phases. It originally provided users with different "skills" placed along a "tree", where they could progress by completing every skill above them. At any time, the user could upgrade the skill, with the final goal of turning it "golden" or "legendary". In November 2022, Duolingo switched to an AI-assisted path, where each user's learning is streamlined without requiring as many decisions. After its switch to this new format, it removed the audio-only lessons it had offered for certain languages. Duolingo also provides a competitive space. In Leagues, people can compete against their friends or see how they stack up against the rest of the world in randomly selected groupings of up to 30 users. Rankings in leagues are determined by the amount of "XP" (eXperience Points) earned in a week. Badges in Duolingo represent achievements earned from completing specific objectives or challenges. Players have reported that gamification has led to cheating, hacking, and incentivized game strategies that conflict with actual learning. Duolingo provides features that allow teachers to track their students' progress. Most of its language-learning features are free, but it has periodic advertising in both its mobile and web browser applications, which users can remove by paying a subscription fee or promoting referral links. This program, known as "Super Duolingo", includes benefits such as unlimited hearts (retries), level skipping, no ads, and progress quizzes. Duolingo currently offers courses in the following languages:

 Arabic
 Catalan
 Chinese (Cantonese)
 Chinese (Mandarin)
 Czech 
 Danish
 Dutch
 English
 Esperanto
 Finnish 
 French 
 German 
 Greek 
 Guaraní
 Haitian Creole
 Hawaiian 
 Hebrew 
 High Valyrian 
 Hindi 
 Hungarian 
 Indonesian 
 Irish 
 Italian 
 Japanese
 Klingon
 Korean 
 Latin 
 Navajo
 Norwegian 
 Polish 
 Portuguese 
 Romanian 
 Russian 
 Scottish Gaelic 
 Spanish 
 Swahili
 Swedish 
 Turkish 
 Ukrainian 
 Vietnamese 
 Welsh

 Yiddish
 Zulu

Duolingo ABC 
Duolingo ABC is a mobile app for young children to learn letters, their sounds, phonics, and other foundational early reading concepts. The app was released in 2020 and is free to use. It does not contain any ads or in-app purchases. The app is available on iOS and Android and is currently in English. Duolingo Math 
Duolingo Math is a mobile app for learning elementary mathematics in a form similar to the original app, released in October 2022. It is currently only available on iOS devices. Duolingo Music 
In March 2023, Duolingo was reportedly developing a new music course that would allow users to learn how to read and play music through its signature gamified learning experience. On October 11, 2023, Duolingo formally unveiled Duolingo Music, a new platform within the existing app that provides basic music learning through piano, drums, and sheet music lessons. Duolingo English Test 

Duolingo English Test (DET) is an online English proficiency test that measures a person's ability to communicate in English. The test is designed to assess a person's proficiency in the areas of reading, writing, speaking, and listening. The Duolingo English Test is entirely computer-based and can be taken from any location with an internet connection. The test is scored on a scale of 10-160, with scores above 120 considered to be proficient in English. The test is adaptive, which means that the difficulty level of the questions adjusts to the test-takers ability level. One of the main advantages of the Duolingo English Test is its convenience and accessibility. Test-takers can take the test at any time, from anywhere in the world, and receive their results within 48 hours. The test is affordable and typically costs less than other English proficiency tests such as TOEFL or IELTS. The Duolingo English Test is recognized by many universities, colleges, and other organizations as an alternative to other English proficiency tests. Business model 
Duolingo had revenue of $1 million in 2016, $13 million in 2017, $36 million in 2018, and $250.77 million in 2021. In May 2022, it was reported that 6.8% of its monthly active users paid for the ad-free version of the app. Duolingo has derived most of its revenue from subscriptions, advertising, and its Duolingo English Test. In April 2020, it passed one million paid subscribers; it reached 2.9 million in March 2022, and 4.8 million at the end of March 2023. Reception

Effectiveness 
A 2017 study found no significant difference between elementary students learning Spanish through the "gamification" of Duolingo and those learning in classroom environments, with both groups demonstrating a similar increase in achievements and self-efficacy. A 2022 study on adults using Duolingo as their only language learning tool, published in the journal Foreign Language Annals, found that the participants that 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. Another 2022 study of Malaysian students learning French, published by the National University of Malaysia Press, found that it facilitated the acquisition of vocabulary, and concluded it was well suited for beginners in this regard. Awards 
In 2013, Apple chose Duolingo as its iPhone App of the Year, a first for an educational application. That year, Duolingo ranked at 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". Duolingo won Best Education Startup at the 2014 Crunchies, and was the most downloaded education app in Google Play in 2013 and 2014. In July 2020, PCMag named it "The Best Free Language Learning App". 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. It won Inc. magazine's Best Workplaces 2018, made Entrepreneur magazine's Top Company Culture List 2018, was among CNBC's "Disruptor 50" lists for 2018 and 2019, and was ranked as one of TIME magazine's 50 Genius Companies. Duolingo was named one of Forbes' "Next Billion-Dollar Startups 2019". In popular culture 

Due to the app's sometimes aggressive sense of humour and frequent reminder notifications, Duolingo's mascot, a green cartoon owl named Duo, has been a subject of Internet memes where the mascot is "evil" and stalks and threatens users if they do not keep using the app. Acknowledging the meme, Duolingo released a video on April Fool's 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 in a large mascot costume) who stares at and follows them until they comply. 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". 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. See also 
 Computer-assisted language learning
 Language education
 Distance education
 Language pedagogy

Notes

References

External links 

 

 
Social networking language-learning websites
Proprietary language learning software
Education companies established in 2011
Internet properties established in 2011
American educational websites
2011 establishments in Pennsylvania
Companies based in Pittsburgh
IOS software
Android (operating system) software
2021 initial public offerings
Companies listed on the Nasdaq