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Duolingo, Inc.
Duolingo logo, featuring the owl mascot Duo
Type of businessPrivate
Available in
HeadquartersPittsburgh, Pennsylvania, United States
Area servedWorld
Founder(s)Luis von Ahn, Severin Hacker
CEOLuis von Ahn
IndustryOnline education, Professional certification, Translation, Crowdsourcing
ServicesLanguage courses, Duolingo English Test, Duolingo for Schools, Tinycards flashcard app
Alexa rankDecrease 863 (May 2018)[2]
Users±300 million people[3]
Launched30 November 2011; 7 years ago (2011-11-30)
Current statusOnline
Native client(s) onAndroid, iOS, Windows Phone, Windows 10 Mobile
Written inSwift,[4] React, Python, Scala[5]

Duolingo (/ˌdˈlɪŋɡ/ DOO-oh-LING-goh) is a platform that includes a language-learning website and app, as well as a digital language proficiency assessment exam. The app and the website are free. Duolingo also offers a premium service for a fee. As of January 2019 the language-learning website and app offer 85 different language courses in 24 languages. The app has about 300 million registered users across the world.[1][6][7][8][9]


The project was started at the end of 2009 in Pittsburgh by Carnegie Mellon University professor Luis von Ahn (creator of reCAPTCHA) and his graduate student Severin Hacker, and then developed along with Antonio Navas, Vicki Cheung, Marcel Uekermann, Brendan Meeder, Hector Villafuerte, and Jose Fuentes.[10][11]

Inspiration for Duolingo came from two places. Luis Von Ahn wanted to create another program that served two purposes in one, what he calls a "twofer".[12] Duolingo originally did this by teaching its users a foreign language while having them translate simple phrases in documents, though the translation feature has since been removed.[13]

Von Ahn was born in Guatemala and saw how expensive it was for people in his community to learn English. Severin Hacker (born in Zug, Switzerland), co-founder of Duolingo, and Von Ahn believe that "free education will really change the world"[14] and wanted to supply people an outlet to do so.

The project was originally sponsored by Luis von Ahn's MacArthur fellowship and a National Science Foundation grant.[15][16] Additional funding was later received in the form of investments from Union Square Ventures and actor Ashton Kutcher's firm, A-Grade Investments.[17][18]

Duolingo started its private beta on 30 November 2011, and accumulated a waiting list of more than 300,000 users.[19] On 19 June 2012, Duolingo launched for the general public. Due to popular interest, Duolingo has received many investments including a $20 million Series C round of investment led by Kleiner Caufield & Byers and a $45 million Series D round of investment led by Google Capital.[20] Duolingo has 95 staff members, of whom many were Google employees,[21] and operates from an office in the Pittsburgh neighborhood of East Liberty.[22][23][24]

On 13 November 2012, Duolingo released their iOS app through the iTunes App Store.[25] The application is a free download and is compatible with most iPhone, iPod and iPad devices.[26] On 29 May 2013, Duolingo released their Android app, which was downloaded about a million times in the first three weeks and quickly became the #1 education app in the Google Play store.[27] As of 2017, the company had a total funding of US$108.3 million.[28] Duolingo received a fifth-round $25 million in July 2017 from Drive Capital, with the funds directed toward creating initiatives such as TinyCards and Duolingo Labs.[29]

Business model[edit]

All language-learning features in Duolingo are free of charge, but it uses periodic advertising in both its mobile and web browser applications,[30][31] which users can remove by paying a subscription fee. It originally employed a crowd sourced business model, where the content came from organizations (such as CNN and BuzzFeed) that paid Duolingo to translate it.[32]

Duolingo is funded by Union Square Venture Partners ($3.3 million in 2011), New Enterprise Associates ($15 million), Kleiner Perkins Caufield & Byers ($20 million), Google Capital ($45 million), Ashton Kutcher's A-Grade Investments, and Tim Ferriss.[33][34][35]

Language courses[edit]

Courses for English speakers[edit]

As of 16 January 2017, 32 courses are available to the public in English, three of which are constructed languages, and those three include two fictional languages.[36][37][38] In this list, the courses are ordered by number of active learners.


As of January 2019, five courses for English speakers are in development (ordered by progression percentage towards completion):[43][44]

Courses unavailable in English[edit]

Duolingo offers language courses for speakers of languages other than English, but all available languages offer at least English as a course. The Catalan and Guarani courses are exclusive to Spanish speakers.

Courses available in other languages[edit]

As of 18 November 2018, the following languages are available to speakers of languages other than English:[50]

  • Arabic: English, French, German, Swedish, Spanish(#)
  • Bengali: English(#)
  • Chinese: English, Spanish, French[51], German(#), Italian(β)[52], Japanese[53], Korean(β)[54]
  • Czech: English
  • Danish: English(#)[55]
  • Dutch: English, German(#)[56]
  • French: English, Spanish, Italian, German, Portuguese
  • German: English, Spanish, French
  • Greek: English
  • Hindi: English
  • Hungarian: English
  • Indonesian: English
  • Italian: English, French, German, Spanish(β)
  • Japanese: English
  • Korean: English
  • Polish: English
  • Portuguese: English, Spanish, French, German, Italian, Esperanto(β)
  • Punjabi: English(#)
  • Romanian: English
  • Russian: English, German, French, Spanish, Swedish(#)
  • Spanish: English, French, Italian, Portuguese, German, Catalan, Guarani, Esperanto, Russian, Swedish(#)[57]
  • Tagalog: English(#)
  • Tamil: English(#)
  • Telugu: English(#)
  • Thai: English
  • Turkish: English, German, Russian, French(#)
  • Ukrainian: English
  • Vietnamese: English

(#) = course still in development (β) = Course still in beta version

Number of languages
available for speakers of:
On app On website
German 3 3
Turkish 2 4
Spanish 8 9
Greek 1 1
Dutch 1 1
French 5 5
Hungarian 1 1
Czech 1 1
Italian 3 4
Arabic 4 5
Indonesian 1 1
Korean 1 1
Ukrainian 1 1
Vietnamese 1 1
Japanese 1 1
Russian 4 5
Thai 1 1
Hindi 1 1
Chinese 2 2
Portuguese 4 6
Polish 1 1
Romanian 1 1
Bengali 2
Punjabi 1
Tagalog 1
Tamil 1
Telugu 1


Presentation at Wikimania about Duolingo.

Duolingo mimics the structure of video games in several ways in order to engage its users. There is a reward system in which users acquire "lingots", an in-game currency that can be spent on features such as character customizations or bonus levels (both available on the mobile app only). There are public leaderboards in which people can compete against their friends or see how they stack up against the rest of the world. The level system that Duolingo uses is XP (experience points), a numerical system that represents a user's skill level. Badges in Duolingo represent achievements that are earned from completing specific objectives or challenges.[58]

Duolingo Clubs[edit]

Duolingo Clubs was launched on 20 December 2016, with the intention of promoting competitiveness and relations between users, adding more "fun" to the course, which increases learning motivation. In Duolingo Clubs there is a weekly ranking of the experience acquired in the lessons, there are badges (achievements) to acquire, among other implements. Duolingo Clubs are available on the mobile versions of iOS, Android and Windows Phone. Although it has a very similar system, it is not completely identical to the website.[59]

Use in schools[edit]

Duolingo provides "Duolingo for Schools" with features designed to allow teachers to track their students. In 2012, an effectiveness study concluded that Duolingo usage for Spanish study was more effective than classroom language learning alone, but that it was less effective for advanced language learners.[60] One proposed reason for this is that the direct-translation method that Duolingo primarily uses is more applicable to simple words and phrases than to complex ones; simpler ones can be translated in a more exact manner from one language to another and thus are more conducive to Duolingo's direct-translation method.[61]


Duolingo uses many services in the Amazon Web Services suite of products, including Amazon DynamoDB, Amazon Virtual Private Cloud, nearly 200 virtual instances in Amazon Elastic Compute Cloud (EC2), Amazon Simple Storage Service (S3) and Amazon Relational Database Service (RDS).[62] The server backend is written in the programming language Python.[63] A component called the Session Generator was rewritten in Scala by 2017.[5] The frontend was written in Backbone.js and Mustache but is now primarily in React and Redux. Duolingo provides a single-page web application for desktop computer users and also smart phone applications on Android (both Google Play Store and Amazon Appstore), iOS App Store and Windows Phone platforms. 20% of traffic comes from desktop users and 80% from mobile app users.[62]

In popular culture[edit]

Duolingo's mascot, Duo, has been a subject of an Internet meme in which the mascot will threaten users to keep using the app.[64] Duolingo Push video was released as an April Fools' Day joke in response to the meme.[65][66]

Recognition and awards[edit]

In 2013, Apple chose Duolingo as its iPhone App of the Year, the first time this honor had been awarded to an educational application.[67] Also, Duolingo won Best Education Startup at the 2014 Crunchies,[22] and was the most downloaded app in the Education category in Google Play in 2013 and 2014.[68] In 2015, Duolingo was announced the 2015 award winner in Play & Learning category by Design to Improve Life.[69] In 2018, Duolingo was named to Fast Company's list of the Most Innovative Companies[70] to CNBC's Disruptor 50 list[71] and one of TIME Magazine's 50 Genius Companies.[72]

See also[edit]


  1. ^ a b "Duolingo moving to East Liberty, plans to add employees". The Business Journals. Retrieved 24 March 2016.
  2. ^ "Duolingo". Ranking. Alexa Internet. Retrieved 30 May 2018.
  3. ^ Frederic Lardinois. "Duolingo hires its first chief marketing officer as active user numbers stagnate but revenue grows". Retrieved 21 November 2018.
  4. ^ "Real World Swift – Making Duolingo Blog". making.duolingo.com.
  5. ^ a b "Rewriting Duolingo's engine in Scala – Making Duolingo Blog". making.duolingo.com.
  6. ^ "100M users strong, Duolingo raises $45M led by Google at a $470M valuation to grow language-learning platform". Venture beat. 10 June 2015. Retrieved 21 June 2015.
  7. ^ "Duolingo – Learn Languages for Free". Windows phone. Microsoft. Retrieved 21 November 2014.
  8. ^ Guliani, Parul. "Duolingo Looks To Dominate The Mobile Education Market With New Flashcard App TinyCards". Forbes. Retrieved 17 February 2017.
  9. ^ "By the Numbers: 16 Amazing Duolingo Stats and Facts (October 2017)". DMR. Retrieved 6 November 2017.
  10. ^ Siegler, MG (12 April 2011). "Meet Duolingo, Google's Next Acquisition Target; Learn A Language, Help The Web". TechCrunch. Retrieved 21 November 2014.
  11. ^ "The Duolingo Team". Twitpic.
  12. ^ Mayer-Schönberger, Viktor; Cukier, Kenneth (2014). Learning with Big Data: The Future of Education. Houghton Mifflin Harcourt. pp. 9–10. ISBN 978-0-54435550-7.
  13. ^ "Immersion". duolingo.[dead link]
  14. ^ Olson, Parmy. "Crowdsourcing Capitalists: How Duolingo's Founders Offered Free Education To Millions". Forbes.
  15. ^ "Online Education as a Vehicle for Human Computation". National Science Foundation.
  16. ^ "Learn a language, translate the web". New Scientist.
  17. ^ Todd, Deborah M. (3 July 2012). "Ashton Kutcher backs CMU duo's startup Duolingo". Pittsburgh Post Gazette. Retrieved 13 July 2012.
  18. ^ "The Daily Start-Up: Kutcher-Backed Language Site Duolingo Finds Its Voice". The Wall Street Journal. 19 June 2012. Retrieved 13 July 2012.
  19. ^ Adi Robertson (16 December 2011). "Duolingo will translate the internet while teaching languages". The Verge. Retrieved 3 February 2016.
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  21. ^ "The Google effect: How has the tech giant changed Pittsburgh's commerce and culture?". Pittsburgh Post-Gazette. 7 December 2014. Retrieved 11 January 2015.
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  25. ^ Frederic Lardinois (13 November 2012). "Language Learning Service Duolingo Launches Its First iPhone App". TechCrunch. AOL. Retrieved 18 April 2016.
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  27. ^ Farber, Dan (11 July 2013). "Duolingo brings free language courses to the iPad". C net. Retrieved 21 February 2014.
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  59. ^ What are Duolingo Clubs? from Duolingo support
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External links[edit]