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Duolingo logo.png
Duolingo logo
Web address duolingo.com
Slogan Free language education for the world
Type of site
Online education, Translation, Crowdsourcing
Registration Free
Available in
Launched 30 November 2011; 3 years ago (2011-11-30)
Current status Public

Duolingo /ˈdjɵˌlɪŋɡ/ is a free language-learning and crowdsourced text translation platform. The service is designed so that, as users progress through the lessons, they simultaneously help to translate websites and other documents.[1][2] As of 23 March 2015, Duolingo offers Latin American Spanish, French, German, Brazilian Portuguese, Italian, Dutch, Irish, Danish, Swedish and Turkish courses for English speakers, as well as American English for Spanish, French, German, Portuguese, Italian, Greek, Dutch, Russian, Polish, Turkish, Hungarian, Romanian, Japanese, Hindi, Indonesian, Korean, Vietnamese, and Czech speakers. It also offers many other combinations of languages.[3] It is available on the Web, iOS, Android and Windows Phone 8.1 platforms.[4]

Duolingo started its private beta on 30 November 2011 and accumulated a waiting list of more than 300,000 users.[5] On 19 June 2012, Duolingo launched for the general public. In 2013, Apple chose Duolingo as its iPhone App of the Year, the first time this honor was awarded to an educational application.[6] Duolingo won Best Education Startup at the 2014 Crunchies,[7] and was the most downloaded education app in Google Play in 2013 and 2014.[8] As of January 2014, Duolingo has 60 million users, out of which about 20 million are active.[9]

Education model[edit]

Duolingo offers 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.[10] 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.[11]

Duolingo uses a heavily data-driven approach to education.[12] At each step along the way, the system measures which questions the users struggle with and what sorts of mistakes they make. It then aggregates those data and learns from the patterns it recognizes.

The efficacy of Duolingo's data-driven approach 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.[13] The same study found that Rosetta Stone users took between 55 and 60 hours to learn a similar amount.[14]

Business model[edit]

Duolingo does not charge students to learn a language. Instead, it 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.[15] On 14 October 2013, Duolingo announced it had entered into agreements with CNN and BuzzFeed to translate articles for the companies' international sites.[16][17]

In July 2014, Duolingo started a language certification service as a new business model (see #Duolingo Test Center).

Venture capitalists and investment firms that hold a stake in Duolingo include Fred Wilson,[18] New Enterprise Associates,[19] Union Square Ventures,[20] and Ashton Kutcher's firm A-Grade Investments.[21][22]


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 also with Antonio Navas, Vicki Cheung, Marcel Uekermann, Brendan Meeder, Hector Villafuerte, and Jose Fuentes.[1][23] The project was originally sponsored by Luis von Ahn's MacArthur fellowship and a National Science Foundation grant[24][25] and is mainly written in the programming language Python.[26] Additional funding was later received in the form of an investment from Union Square Ventures and actor Ashton Kutcher's firm A-Grade Investments.[21][22]

As of 19 June 2014, Duolingo had 32 staff members (where many of them are ex-Google employees[27]) and operates from an office in the Pittsburgh neighborhood of Shadyside near Carnegie Mellon's campus.[7][28]

As of 2 June 2014, Duolingo has reached 30 million users.[7]

On 13 November 2012 Duolingo released their iOS app through the iTunes App Store.[29] The app can be downloaded for free and is compatible with most iPhone, iPod and iPad devices.[30] 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.[31] Duolingo then released both a Google Glass App (glassware) and support for Android Wear.[32] A visual history can be found here.[33]

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".[34] The result was The Language Incubator, which was released on 9 October 2013.[35][36] 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.[37] 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.[38] Other courses created by the Duolingo community include English from Turkish, Dutch and Hungarian, as well as French and 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 behalf, which either misled the student or counted a correct answer wrong, they may submit a report detailing what happened.

As of March 23, 2015, ten courses were available to the public from/in English: Spanish, French, German, Italian, Portuguese, Dutch, Irish, Swedish, Danish, and Turkish. Coming soon to the English speaking world (in order of progression percentage towards completion): Ukrainian (100%), Hungarian (93%), Esperanto (90%), Norwegian Bokmål (78%), Russian (70%), Romanian (27%), Vietnamese (19%), Polish (16%), Modern Greek (7%), Yiddish (0%), and Hebrew (0%), but soon: Japanese, Chinese, Hindi, Modern Arabic, Korean, Czech, Bulgarian, Serbian, Slovak, Finnish (As of March 24, 2015).[39][40][41][42]

Usually, a course teaching English from another language will be made before the reverse (a course teaching that language for English speakers). Once that course reaches Phase 3, the course for English speakers is started, presumably with much of the work already done. Exceptions to this rule happen when a language has few speakers and/or most speakers already know English, e.g. Irish. Courses teaching English for speakers of Chinese, Arabic, Indonesian, Czech, Japanese, and Korean are in Phase 2, at about 90% each. English courses for Hindi and Greek speakers are both in Phase 3. Therefore, it is relatively safe to assume that all of these languages will have courses teaching them for English speakers at some point in time.[39][41]

Duolingo Test Center[edit]

Duolingo launched Duolingo Test Center on 22 July 2014. It is an online language certification platform that can be taken by Web, iOS or Android, where tests are proctored through microphone and camera. The test requires 20 minutes to finish, costs 20 USD, and graded within 48 hours on a scale between 0 and 10.[43] According to a study conducted by University of Pittsburgh, there is a substantial correlation between the scores from Duolingo Test Center and TOEFL iBT.[44][45]

oDesk adapts the Test Center score as one of their official qualifications with which freelance workers can prove their English fluency.[46][47] Duolingo collaborates with LinkedIn to allow the score to be easily incorporated into a user's résumé page.[43] 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.[48][49]

In December 2014, Duolingo Test Center was selected as Google Play Best Apps of 2014 by Google.[50][51]

Duolingo for Schools[edit]

Duolingo is increasingly used in classrooms. For example, in Costa Rica and Guatemala, Duolingo has been used in public schools as a pilot project run by the government.[52]

In January 2015, Duolingo released Duolingo for Schools, for providing a teacher with a centralized dashboard that can display their students’ progress.[9] The dashboard enables teachers to understand individual student's weakness and strength at each skill, and helps them to come up with best ways to teach a language.[53]


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).[54]

Duolingo offers a single page web application for desktop computer users and also smart phone applications on Android (both Google Play Store and Amazon Appstore), iPhone (App Store) and Windows Phone platforms. 20% of traffic comes from desktop users and 80% from mobile app users.[54]

See also[edit]


  1. ^ a b MG Siegler (April 12, 2011). "Meet Duolingo, Google's Next Acquisition Target; Learn A Language, Help The Web". TechCrunch. Retrieved 2014-11-21. 
  2. ^ Christopher Mims (May 2, 2011). "Translating the Web While You Learn". Technology Review. Retrieved 2014-11-21. 
  3. ^ "Duolingo: Language Courses". Retrieved 26 August 2014. 
  4. ^ "Duolingo - Learn Languages for Free". Retrieved 2014-11-21. 
  5. ^ "We have a blog!". Duolingo Blog. 
  6. ^ "Duolingo snags iPhone App of the Year". Gigaom.com. 2013-12-17. Retrieved 2014-02-21. 
  7. ^ a b c Luis. "Duolingo turns two today!". Retrieved 2014-11-21. 
  8. ^ "Google Play reveals the most downloaded apps, games and entertainment content from 2014". The Next Web. 2014-12-11. Retrieved 2014-12-29. 
  9. ^ a b "Duolingo For Schools Is Free, And It May Change The EdTech Market". Forbes. 2015-01-08. Retrieved 2015-01-09. 
  10. ^ "Ready, Set, Practice!". Duolingo Blog. Retrieved 8 November 2012. 
  11. ^ My Three Months of Duolingo: "There are 2014 words listed in my Duolingo vocabulary". (http://olimo.livejournal.com/, 2012-09-19)
  12. ^ "Duolingo's Data-Driven Approach to Education". Blog.duolingo.com. 2013-01-31. Retrieved 2014-02-21. 
  13. ^ "Duolingo Effectiveness Study". unpublished. Retrieved 2013-08-23. 
  14. ^ Kelleher, Kevin (2013-05-30). "Say what? Duolingo points to data's important role in online education". Pandodaily.com. Retrieved 2014-02-21. 
  15. ^ Simonite, Tom (2012-11-29). "The Cleverest Business Model in Online Education". Technologyreview.com. Retrieved 2014-02-21. 
  16. ^ "Duolingo now translating BuzzFeed and CNN". Duolingo. 14 October 2013. Retrieved 7 November 2013. 
  17. ^ "BuzzFeed Expands Internationally In Partnership With Duolingo". BuzzFeed. 14 October 2013. Retrieved 7 November 2013. 
  18. ^ Fred Wilson. "Feature Friday: The Dashboard". avc.com. Retrieved 28 March 2015. 
  19. ^ "Duolingo - NEA - New Enterprise Associates". nea.com. Retrieved 28 March 2015. 
  20. ^ "Portfolio - Union Square Ventures". usv.com. Retrieved 28 March 2015. 
  21. ^ a b Todd, Deborah M. (3 July 2012). "Ashton Kutcher backs CMU duo's startup Duolingo". Pittsburgh Post Gazette. Retrieved 13 July 2012. 
  22. ^ a b "The Daily Start-Up: Kutcher-Backed Language Site Duolingo Finds Its Voice". Wall Street Journal. 19 June 2012. Retrieved 13 July 2012. 
  23. ^ "The Duolingo Team". Twitpic. 
  24. ^ "Online Education as a Vehicle for Human Computation". National Science Foundation. 
  25. ^ "Learn a language, translate the web". NewScientist. 
  26. ^ "What language is Duolingo written in?". Quora. Retrieved 2014-02-21. 
  27. ^ "The Google effect: How has the tech giant changed Pittsburgh's commerce and culture?". Pittsburgh Post-Gazette. 2014-12-07. Retrieved 2015-01-11. 
  28. ^ "Duolingo launching on Android; plans move to bigger office". Bizjournals.com. 2013-05-29. Retrieved 2014-02-21. 
  29. ^ "Duolingo on the go. Our iPhone App is here!". Duolingo. 13 November 2012. Retrieved 27 November 2012. 
  30. ^ "Duolingo - Learn Spanish, French, German, Portuguese, and Italian for free". iTunes App Store. Apple. Retrieved 29 April 2013. 
  31. ^ Farber, Dan (2013-07-11). "Duolingo brings free language courses to the iPad". News.cnet.com. Retrieved 2014-02-21. 
  32. ^ "Introducing Duolingo for Google Glass and Android Wear. Learn a language, at…". Plus.google.com. Retrieved 20 January 2015. 
  33. ^ "Duolingo - Learn Spanish, French, German, Portuguese, Italian and English for free". duolingo.com. Retrieved 28 March 2015. 
  34. ^ von Ahn, Luis. "Reddit IAmA". Retrieved 3 June 2013. 
  35. ^ Olson, Parmy. "Duolingo Takes Online Teaching To The Next Level, By Crowd Sourcing New Languages". Forbes. 
  36. ^ "Discussion". Duolingo. Retrieved 9 October 2013. 
  37. ^ "Duolingo 'incubator' aims to crowdsource language teaching". Edition.cnn.com. 2013-10-15. Retrieved 2014-02-21. 
  38. ^ "English from Russian is now available in beta!". Duolingo.com. Retrieved 2014-02-21. 
  39. ^ a b "Duolingo - Learn Spanish, French, German, Portuguese, Italian and English for free". Duolingo.com. Retrieved 23 March 2015. 
  40. ^ "Duolingo". Incubator.duolingo.com. Retrieved 23 March 2015. 
  41. ^ a b "Duolingo". Incubator.duolingo.com. Retrieved 23 March 2015. 
  42. ^ "DuoInc Tracker". Moviemap.me. Retrieved 23 March 2015. 
  43. ^ a b "Duolingo Launches Its Certification Program To Take On TOEFL". Techcrunch. Retrieved 27 December 2014. 
  44. ^ "Proficient Enough?". Inside Higher Ed. Retrieved 27 December 2014. 
  45. ^ "Validity, reliability, and concordance of the Duolingo English Test". Feifei Ye, PhD, University of Pittsburgh. Retrieved 27 December 2014. 
  46. ^ "Duolingo offers language-certification tests via mobile devices". LA Times. Retrieved 27 December 2014. 
  47. ^ "Why Duolingo (and Google) are Entering the Standardized Test Game". Fast Company. Retrieved 27 December 2014. 
  48. ^ "Duolingo Founder: Personalized, Adaptive Education Is More Efficient". re/code. Retrieved 27 December 2014. 
  49. ^ "Reinventing English Proficiency Tests". Carnegie Mellon University, Homepage Stories. Retrieved 27 December 2014. 
  50. ^ "Google Play store shares its ‘Best Apps of 2014′ list". 9To5Google. Retrieved 27 December 2014. 
  51. ^ "Best Apps of 2014". Google Play. Retrieved 27 December 2014. 
  52. ^ "Duolingo Launches Free Language Learning Platform For Schools". TechCrunch. 2015-01-08. Retrieved 2015-01-09. 
  53. ^ "A Clever Plan to Teach Schoolkids New Languages With a Free App". Wired. 2015-01-08. Retrieved 2015-01-09. 
  54. ^ a b "AWS Case Study: Duolingo". Amazon Web Services, Inc. Retrieved 28 March 2015. 

External links[edit]