world european union restricted 1 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 60 2 slogan s free language education for the world website www.duolingo.com written in python alexa rank 862 september 2016 update 3 advertising yes registration yes users 120 million 2 available in multilingual english american english esperanto french european french spanish latin american spanish portuguese brazilian italian dutch german modern hebrew polish romanian russian turkish hungarian japanese chinese mandarin hindi indonesian greek modern standard arabic korean vietnamese ukrainian czech welsh irish launched 30 november 2011 ; 4 years ago 2011 11 30 current status online native client s on android ios windows phone play media presentation at wikimania about duolingo duolingo du o l o doo oh ling goh or dju o l o dyoo oh ling goh is a free language learning platform that includes a language learning website and app as well as a digital language proficiency assessment exam . duolingo offers all its language courses free of charge . as of april 2016 the language learning website and app offer 59 different language courses across 23 languages ; with 23 additional courses in development . the app is available on ios android and windows 8 and 10 platforms with about 120 million registered users across the world . 2 4 5 contents 1 history 2 business model 2.1 crowdsourced translation 2.2 investors 3 products 3.1 language courses 3.1.1 currency 3.1.2 language incubator 3.1.3 courses for users who know english 3.1.4 courses not available in english 3.2 duolingo test center 3.3 duolingo for schools 3.4 tinycards 4 infrastructure 5 recognition and awards 6 see also 7 references 8 external links history edit 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 . 6 7 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 . 8 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 hacker born in zug switzerland co founder of duolingo and von ahn believe that free education will really change the world 9 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 . 10 11 additional funding was later received in the form of investments from union square ventures and actor ashton kutcher s firm a grade investments . 12 13 duolingo started its private beta on november 30 2011 and accumulated a waiting list of more than 300 000 users . 14 on june 19 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 . 15 duolingo has 60 staff members of whom many were google employees 16 and operates from an office in the pittsburgh neighborhood of shadyside near carnegie mellon s campus . 17 18 on november 13 2012 duolingo released their ios app through the itunes app store . 19 the application is a free download and is compatible with most iphone ipod and ipad devices . 20 on may 29 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 . 21 duolingo then released both a google glass app glassware and support for android wear . 22 business model edit core services of the platform are available for free . duolingo uses only very limited advertising in its android app . there are no subscription fees for the tutorials . however there were instances when the platform has been used for paid translation purposes . 23 in july 2014 duolingo started a language certification service test center as a new business model . in june 2015 a 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 . 24 according to luis von ahn in order to offset the over 40 000 a day cost of developer salaries server costs etc. duolingo now charges a fee to maintain a streak freeze at the request of users . 25 crowdsourced translation edit to earn money duolingo originally employed a crowd sourced business model where members of the public were invited to translate content and vote on translations . the content came from organizations that pay duolingo to translate it . documents could be added to duolingo for translation with an upload account which had to be applied for . 26 on october 14 2013 duolingo announced it had entered into agreements with cnn and buzzfeed to translate articles for the companies international sites . 27 investors edit as of 2015 the company has been valued at usd 470 million with a total funding of usd 83.3 million . 28 venture capitalists private investors and other investor firms that hold a stake in duolingo include fred wilson 29 union square ventures 30 new enterprise associates 31 ashton kutcher 12 13 kleiner perkins caufield & byers google capital 30 and tim ferriss . 32 products edit language courses edit duolingo provides written lessons and dictation with speaking practice for more advanced users . it has a gamified skill tree that users can progress through 19 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 . 33 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 would start with four lives on early lessons 33 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 . 34 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 and 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 . 35 duolingo uses a data driven approach to lesson planning . 36 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 a 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 university 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 . 37 the same study found that rosetta stone users took between 55 and 60 hours to learn a similar amount . 38 currency edit a lingot a portmanteau of the words lingo and ingot is the currency of duolingo . 39 users gain lingots by leveling up finishing a skill maintaining a usage streak for a total of seven days inviting others to duo via social media and by uploading documents to the immersion . items available in the lingot store include power ups practice and bonus skills . users of the mobile apps can also customize the appearance of the duolingo mascot which is by default the green owl . 39 this feature is not available on the browser version . a hidden bonus skill included in some courses is christmas which is only available in the period surrounding christmas . other bonus skills include flirting and idioms and proverbs . language incubator edit instead of slowly adding additional languages ceo luis von ahn announced on may 29 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 . 40 the result was the language incubator 41 which was released on october 9 2013 . 42 43 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 . 44 the first course entirely created by the duolingo community through the incubator was learning english from russian which launched in beta on december 19 2013 . 45 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 for users who know english edit as of 2 september 2016 update 19 courses were available to the public from english ordered by number of learners latin american spanish french german italian brazilian portuguese dutch swedish russian irish turkish danish norwegian bokm l polish esperanto ukrainian welsh hebrew vietnamese hungarian greek 8 courses for english speakers are currently in development ordered by progression percentage towards completion 46 47 romanian swahili 48 czech 49 indonesian 50 hindi klingon korean 51 yiddish courses not available in english edit catalan and guarani are available as a second language for spanish speakers . they are currently the only languages offered on duolingo which are not available to english speakers . most other languages only offer a course into english . as of june 2 2016 update languages offering additional courses some still in development are spanish with courses into french portuguese italian german and esperanto as well as the catalan and guarani courses mentioned