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Duolingo logo.png
Headquarters Pittsburgh, USA
Founder(s) Luis von Ahn, Severin Hacker
CEO Luis von Ahn
Industry Online education, Professional certification, Translation, Crowdsourcing
Services Language courses, Duolingo Test Center, Duolingo for Schools
Employees 42
Slogan(s) Free language education for the world
Website duolingo.com
Written in Python
Alexa rank positive decrease 1,446 (September2015)[1]
Advertising no
Registration yes
Available in
Launched 30 November 2011; 3 years ago (2011-11-30)
Current status Online
Native client(s) on Android, iOS, Windows Phone

Duolingo /ˈdjɵˌlɪŋɡ/ is a free language-learning platform that includes a language-learning website and app along with a crowdsourced text translation platform and a language proficiency assessment center. Duolingo is ad-free and offers all its language courses gratis. The language-learning website and app offer over 40 different language courses across 23 languages. The app is available on iOS, Android and Windows 8 and 10 platforms with over 100 million registered users across the world.[2][3]


The project was started 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.[4][5]

Inspiration for Duolingo comes from two places. Luis Von Ahn, creator of reCAPTCHA, wanted to create another program that served two purposes in one, what he calls a “twofer”.[6] Duolingo does this by teaching its users a foreign language while having them translate simple phrases in documents.

Forbes staff member, Parmy Olson revealed the other incentive towards creating Duolingo. Von Ahn was born in Guatemala and saw how expensive it was for people in his community to learn English. Severin (Bavarian) Hacker, co-founder of Duolingo, and Von Ahn believe that “free education will really change the world”[7] and wanted to supply the people an outlet to do so.

The project was originally sponsored by Luis von Ahn's MacArthur fellowship and a National Science Foundation grant.[8][9] Additional funding was later received in the form of investments from Union Square Ventures and actor Ashton Kutcher's firm, A-Grade Investments.[10][11]

Duolingo started its private beta on 30 November 2011 and accumulated a waiting list of more than 300,000 users.[citation needed] On 19 June 2012, Duolingo launched for the general public. Due to popular interest, Duolingo has received many investments including $20 million Series C round of investment led by Kleiner Caufield & Byers.[12] Duolingo has 42 staff members, of whom many were Google employees,[13] and operates from an office in the Pittsburgh neighborhood of Shadyside near Carnegie Mellon's campus.[14][15]

On 13 November 2012 Duolingo released their iOS app through the iTunes App Store.[16] The application is a free download and is compatible with most iPhone, iPod and iPad devices.[17] On 29 May 2013, Duolingo released their Android app, which was downloaded over a million times in the first three weeks and quickly became the #1 education app in the Google Play store.[18] Duolingo then released both a Google Glass App (glassware) and support for Android Wear.[19]

Business model[edit]

Duolingo is ad-free and single users taking language courses are not charged for its services.

Crowdsourced translation[edit]

To earn money, Duolingo employs a crowd sourced business model, where members of the public are invited to translate content and vote on translations. The content comes from organizations that pay Duolingo to translate it. Documents can be added to Duolingo for translation with an upload account which must be applied for.[20] On 14 October 2013, Duolingo announced it had entered into agreements with CNN and BuzzFeed to translate articles for the companies' international sites.[21][22] As of September 2015, no further translation agreements were announced.

2014 Language certification pivot[edit]

In July 2014, Duolingo started a language certification service, Test Center, as a new business model. In June 2015, Duolingo spokesperson confirmed that the company has been backing away from the translation business and in the future will instead focus on language certification and other (not yet announced) business opportunities.[23]


Venture capitalists and investment firms that hold a stake in Duolingo include Fred Wilson,[24] New Enterprise Associates,[25] Google Ventures,[26] Union Square Ventures,[27] and A-Grade Investments.[10][11]


Language courses[edit]

Duolingo provides extensive written lessons and dictation, with speaking practice for more advanced users. It has a gamified skill tree that users can progress through and a vocabulary section where learned words can be practiced.

Users gain "experience points" (XP) as they learn a language, such as when they complete a lesson. Skills are considered "learned" when users complete all the lessons associated with the skill. Users win one point for each correct answer, and lose one for each error, and validate the lesson when they reach 10 points. (In an earlier version, users used to start with four "lives" on early lessons and three on later lessons, a "life" being lost with each mistake.)

Duolingo also includes a timed practice feature, where users are given 30 seconds and twenty questions and awarded a skill point and seven or ten additional seconds (time depends on the length of the question) for each correct answer.[28] This timed practice feature is only available after purchase in the Lingot store for ten lingots, the currency the site uses. As the goal of Duolingo is to get people to learn the language, each skill (containing between 1 to 10 lessons) has a "strength bar" that corresponds to the computer's estimate of how strongly certain words or constructions still exist in the user's memory. After a certain duration of time, strength bars fade, indicating a need for a user to refresh/re-study that lesson, or to "strengthen weak skills." Courses can teach upwards of 2,000 words.[29] Duolingo uses a data-driven approach to lesson planning.[30] At each step along the way, the system measures which questions the users struggle with and what sorts of mistakes they make.

The efficacy of Duolingo's Spanish course has been reviewed by an external study commissioned by the company. Conducted by professors at City University of New York and the University of South Carolina, the study estimated that 34 hours on Duolingo may yield reading and writing ability of a US first-year beginners' course college semester, which takes in the order of 130+ hours. The research did not measure speaking ability. It found that a majority of students dropped out after less than 2 hours of study.[31] The same study found that Rosetta Stone users took between 55 and 60 hours to learn a similar amount.[32]


A Lingot [ling-guht], is the currency of Duolingo. Users gain Lingots by leveling up, finishing a skill, maintaining a usage-streak for a total of seven days, inviting others to Duo via internet and by uploading documents to the Immersion. Items available in the Lingot Store include Power-ups, Practice and Bonus Skills. Users can also change the appearance of the Duolingo mascot, which is by default the green bird, into a more customizable and personable form. A hidden Bonus Skill included in some Languages is "Christmas" only available during winter time. Other Bonus Skills include "Flirting" and "Idioms and Proverbs".

Language incubator[edit]

Instead of slowly adding additional languages, CEO Luis von Ahn announced on 29 May 2013 that they would create the tools necessary for the community to build new language courses, with the hope to introduce more languages and "empower other experts and people passionate about a specific language to lead the way".[33] The result was The Language Incubator, which was released on 9 October 2013.[34][35] In addition to helping the community create courses for widely spoken languages, the Duolingo Incubator also aims to help preserve some of the less popular languages such as Latin, Mayan and Basque.[36] The first course entirely created by the Duolingo community through the Incubator was learning English from Russian, which launched in beta on 19 December 2013.[37] Other courses created by the Duolingo community include English from Turkish, Dutch and Hungarian, as well as French and Brazilian Portuguese from Spanish.

The Incubator has three Phases. First, when sufficient interest to contribute to a new course has been received from volunteers fluent in both languages (a requirement for application), the course begins in "Phase 1: Not Yet Released," . The second phase, "Phase 2: Released in Beta," begins when the course has been fully prepared and is ready for open beta testing. Finally, "Phase 3: Graduated from Beta" is when a course is considered relatively stable. The reason complete courses remain in the Incubator is that Moderators/Contributors can continue to improve the course. For example, if a student gets a question wrong but notices there was an error on the program's part, which either misled the student or counted a correct answer wrong, they may submit a report detailing what happened.

Courses from/ in English[edit]

As of 3 August 2015, 13 courses were available to the public from/in English:

12 courses for English speakers are currently in development (ordered by progression percentage towards completion):

Duolingo Test Center[edit]

Duolingo launched Duolingo Test Center on 22 July 2014. It is an online language certification platform that can be taken on the Web, iOS or Android, where tests are proctored through microphone and camera. The test requires 20 minutes to finish, costs 20 USD, and is graded within 48 hours on a scale between 0 and 10.[42] According to a study conducted by University of Pittsburgh, there is a substantial correlation between the scores from Duolingo Test Center and TOEFL iBT.[43][44]

oDesk has adapted the Test Center score as one of their official qualifications with which freelance workers can prove their English fluency.[45][46] Duolingo is also collaborating with LinkedIn to allow the score to be easily incorporated into a user's résumé page.[42] Duolingo is working with twelve US universities, including Carnegie Mellon University, to study if the score can be reliably used as one of their admission qualifications.[47][48]

Duolingo for Schools[edit]

Duolingo has been used in schools. For example, in Costa Rica and Guatemala, Duolingo has been used in public schools as a pilot project run by the government.[49]

In January 2015, Duolingo released Duolingo for Schools, to provide teachers with a centralized dashboard that can display their students’ progress.[50] The dashboard helps teachers understand each individual student's weaknesses and strengths at each skill, and helps them optimize their language-teaching methods.[51]


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).[52] The server backend is mainly written in the programming language Python,[53] and the frontend in Backbone.js and Mustache. 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.[52]

Recognition and awards[edit]

In 2013, Apple chose Duolingo as its iPhone App of the Year, the first time this honor was awarded to an educational application.[54] Also, Duolingo won Best Education Startup at the 2014 Crunchies,[14] and was the most downloaded app in the Education category in Google Play in 2013 and 2014.[55]

See also[edit]


  1. ^ "Alexa Ranking". Alexa Internet. Retrieved 21 July 2015. 
  2. ^ "100M users strong, Duolingo raises $45M led by Google at a $470M valuation to grow language-learning platform". Retrieved 2015-06-21. 
  3. ^ "Duolingo - Learn Languages for Free". Retrieved 2014-11-21. 
  4. ^ MG Siegler (April 12, 2011). "Meet Duolingo, Google's Next Acquisition Target; Learn A Language, Help The Web". TechCrunch. Retrieved 2014-11-21. 
  5. ^ "The Duolingo Team". Twitpic. 
  6. ^ Mayer-Schönberger, Viktor; Cukier, Kenneth (2014). Learning with Big Data: The Future of Education. Houghton Mifflin Harcourt. pp. 9–10. ISBN 9780544355507. 
  7. ^ Parmy Olson. "Crowdsourcing Capitalists: How Duolingo's Founders Offered Free Education To Millions". Forbes. 
  8. ^ "Online Education as a Vehicle for Human Computation". National Science Foundation. 
  9. ^ "Learn a language, translate the web". NewScientist. 
  10. ^ a b Todd, Deborah M. (3 July 2012). "Ashton Kutcher backs CMU duo's startup Duolingo". Pittsburgh Post Gazette. Retrieved 13 July 2012. 
  11. ^ a b "The Daily Start-Up: Kutcher-Backed Language Site Duolingo Finds Its Voice". Wall Street Journal. 19 June 2012. Retrieved 13 July 2012. 
  12. ^ "We have a blog!". Duolingo Blog. 
  13. ^ "The Google effect: How has the tech giant changed Pittsburgh's commerce and culture?". Pittsburgh Post-Gazette. 2014-12-07. Retrieved 2015-01-11. 
  14. ^ a b Luis. "Duolingo turns two today!". Retrieved 2014-11-21. 
  15. ^ "Duolingo launching on Android; plans move to bigger office". Bizjournals.com. 2013-05-29. Retrieved 2014-02-21. 
  16. ^ "Duolingo on the go. Our iPhone App is here!". Duolingo. 13 November 2012. Retrieved 27 November 2012. 
  17. ^ "Duolingo - Learn Spanish, French, German, Portuguese, and Italian for free". iTunes App Store. Apple. Retrieved 29 April 2013. 
  18. ^ Farber, Dan (2013-07-11). "Duolingo brings free language courses to the iPad". News.cnet.com. Retrieved 2014-02-21. 
  19. ^ "Introducing Duolingo for Google Glass and Android Wear. Learn a language, at…". Plus.google.com. Retrieved 20 January 2015. 
  20. ^ Simonite, Tom (2012-11-29). "The Cleverest Business Model in Online Education". Technologyreview.com. Retrieved 2014-02-21. 
  21. ^ "Duolingo now translating BuzzFeed and CNN". Duolingo. 14 October 2013. Retrieved 7 November 2013. 
  22. ^ "BuzzFeed Expands Internationally In Partnership With Duolingo". BuzzFeed. 14 October 2013. Retrieved 7 November 2013. 
  23. ^ Frederic Lardinois. "Duolingo Raises $45 Million Series D Round Led By Google Capital, Now Valued At $470M". techcrunch.com. Retrieved 19 September 2015. 
  24. ^ Fred Wilson. "Feature Friday: The Dashboard". avc.com. Retrieved 28 March 2015. 
  25. ^ "Duolingo - NEA - New Enterprise Associates". nea.com. Retrieved 28 March 2015. 
  26. ^ "A startup that promises to teach you 9 languages just raised $45 million from Google". Retrieved 10 June 2015. 
  27. ^ "Portfolio - Union Square Ventures". usv.com. Retrieved 28 March 2015. 
  28. ^ "Ready, Set, Practice!". Duolingo Blog. Retrieved 8 November 2012. 
  29. ^ My Three Months of Duolingo: "There are 2014 words listed in my Duolingo vocabulary". (http://olimo.livejournal.com/, 2012-09-19)
  30. ^ "Duolingo's Data-Driven Approach to Education". Blog.duolingo.com. 2013-01-31. Retrieved 2014-02-21. 
  31. ^ "Duolingo Effectiveness Study" (PDF). unpublished. Retrieved 2013-08-23. 
  32. ^ Kelleher, Kevin (2013-05-30). "Say what? Duolingo points to data's important role in online education". Pandodaily.com. Retrieved 2014-02-21. 
  33. ^ von Ahn, Luis. "Reddit IAmA". Retrieved 3 June 2013. 
  34. ^ Olson, Parmy. "Duolingo Takes Online Teaching To The Next Level, By Crowd Sourcing New Languages". Forbes. 
  35. ^ "Discussion". Duolingo. Retrieved 9 October 2013. 
  36. ^ "Duolingo 'incubator' aims to crowdsource language teaching". Edition.cnn.com. 2013-10-15. Retrieved 2014-02-21. 
  37. ^ "English from Russian is now available in beta!". Duolingo.com. Retrieved 2014-02-21. 
  38. ^ "Duolingo". duolingo.com. 
  39. ^ "Duolingo". duolingo.com. 
  40. ^ "Duolingo – Learn Spanish, French, German, Portuguese, Italian and English for free". Duolingo.com. Retrieved 5 April 2015. 
  41. ^ "Duolingo: Incubator". Duolingo.com. Retrieved 28 May 2015. 
  42. ^ a b "Duolingo Launches Its Certification Program To Take On TOEFL". Techcrunch. Retrieved 27 December 2014. 
  43. ^ "Proficient Enough?". Inside Higher Ed. Retrieved 27 December 2014. 
  44. ^ "Validity, reliability, and concordance of the Duolingo English Test" (PDF). Feifei Ye, PhD, University of Pittsburgh. Retrieved 27 December 2014. 
  45. ^ "Duolingo offers language-certification tests via mobile devices". LA Times. Retrieved 27 December 2014. 
  46. ^ "Why Duolingo (and Google) are Entering the Standardized Test Game". Fast Company. Retrieved 27 December 2014. 
  47. ^ "Duolingo Founder: Personalized, Adaptive Education Is More Efficient". re/code. Retrieved 27 December 2014. 
  48. ^ "Reinventing English Proficiency Tests". Carnegie Mellon University, Homepage Stories. Retrieved 27 December 2014. 
  49. ^ "Duolingo Launches Free Language Learning Platform For Schools". TechCrunch. 2015-01-08. Retrieved 2015-01-09. 
  50. ^ "Duolingo For Schools Is Free, And It May Change The EdTech Market". Forbes. 2015-01-08. Retrieved 2015-01-09. 
  51. ^ "A Clever Plan to Teach Schoolkids New Languages With a Free App". Wired. 2015-01-08. Retrieved 2015-01-09. 
  52. ^ a b "AWS Case Study: Duolingo". Amazon Web Services, Inc. Retrieved 28 March 2015. 
  53. ^ "What language is Duolingo written in?". Quora. Retrieved 2014-02-21. 
  54. ^ "Duolingo snags iPhone App of the Year". Gigaom.com. 2013-12-17. Retrieved 2014-02-21. 
  55. ^ "Google Play reveals the most downloaded apps, games and entertainment content from 2014". The Next Web. 2014-12-11. Retrieved 2014-12-29. 

External links[edit]