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Duolingo

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Duolingo (/ˌduːoʊˈlɪŋɡoʊ/ 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 company uses the freemium model; the app and the website are accessible without charge, although Duolingo also offers a premium service for a fee.

Duolingo, Inc.
Duolingo logo, featuring the owl mascot Duo
Screenshot
File:Duolingo homepage.png
Duolingo homepage
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
Revenue36 million USD in 2018[1]
Employees200+[2]
URLwww.duolingo.com
AdvertisingYes
RegistrationYes
Users±300 million users[3]
Launched30 November 2011; 12 years ago (2011-11-30) (private beta)
19 June 2012; 11 years ago (2012-06-19) (public release)
Current statusOnline
Native client(s) onAndroid, iOS, Windows Phone, Windows 10 Mobile
Written inSwift,[4] React, Python, Scala[5]

As of November 2019 the language-learning website and app offer 94 different language courses in 23 languages. The app has over 300 million registered users across the world.[7][8][9][10]

History

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.[11][12][13]

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".[14] 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.[15]

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 current CTO, and Von Ahn believe that "free education will really change the world"[16] 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.[17][18]

On October 19, 2011, during in its "Early Stage Venture" stage Duolingo raised $3.3 million from a Series A first-round of funding, led by Union Square Ventures, with participation from author Tim Ferriss and actor Ashton Kutcher's firm, A-Grade Investments [19][20][21]

Duolingo launched into private beta a month later on November 30, 2011, and accumulated a waiting list of more than 300,000 users.[22][23][24]

On June 19, 2012, Duolingo later launched for the general public.[25]

On September 17, 2012, while still in its "Early Stage Venture" stage, Duolingo raised $15 million from a Series B second-round of funding led by New Enterprise Associates, with participation from Union Square Ventures bringing Duolingo's total funding to $18.3 million.[26]

On 13 November 2012, Duolingo released their iOS app through the iTunes App Store.[27] The application is a free download and is compatible with most iPhone, iPod and iPad devices.[28]

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.[29]

On June 19, 2013, one year after launching for the general public, Duolingo passed 4 million users, all through word of mouth, [30] and on November 21, 2013, Duolingo reached 15 million users[30]

On February 18, 2014, Duolingo entered its "Late Stage Venture" stage, and raised $20 million from a Series C third-round of funding led by Kleiner Caufield & Byers.[31] It was reported Duolingo had about 25 million registered users, 12.5 million active users, and 34 employees.[32] On June 2, 2014, Duolingo passed 30 million users[30]

On June 10, 2015, Duolingo raised $45 million from a Series D fourth-round of funding led by Google Capital, bringing its total funding to $83.3 million, a valuation of $470 million, as well as passing 100 million users.[33][34][35]

In April 2016 it was reported that Duolingo had 17 million monthly users.[36][37]

On July 25, 2017, that Duolingo raised $25 million from a Series E fifth-round of investment from Drive Capital, bringing its total funding to $108.3 million, a valuation of $700 million, as well as passing 200 million users and having 25 million monthly users.[38][39] It was reported that Duolingo had 95 employees,[40] and the funds would be directed toward creating initiatives such as TinyCards and Duolingo Labs.[41]

On August 1, 2018, it was reported Duolingo passed 300 million users.[42]

On December 4, 2019, it was announced that Duolingo raised $30 million in a series F sixth-round of investment from Alphabet’s investment company CapitalG, bringing a total funding of $138.3 million, a valuation of $1.5 billion, reporting 30 million monthly active learners.[43] Duolingo will use the funds on developing new products and expanding its team. Expanding the team will span a variety of positions, including in engineering, business development, design, curriculum and content creators, community outreach and marketing.[44]

During 2019, Duolingo grew from 170 staff members,[45] to 200 employees,[46] of whom many were Google employees,[47] with headquarters in the Pittsburgh neighborhood of East Liberty,[48][49][50] and offices in New York, Seattle and Beijing.[51] Of Duolingo’s 200 employees, 166 work in its East Liberty headquarters, 17 work in New York, 8 in Seattle and 8 in China.[52]

Duolingo had a revenue of $1 million in 2016, $13 million in 2017,[53] $36 million in 2018,[54] and is projected to hit $86 million in 2019.[55]

Business model

Most language-learning features in Duolingo are free of charge, but it uses periodic advertising in both its mobile and web browser applications,[56][57] which users can remove by paying a subscription fee. This feature, which is named ‘Duolingo Plus’, includes benefits such as having unlimited hearts and being able to skip levels. 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.[58]

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.[59][60][61]

Infrastructure

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.[better source needed] 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

Duolingo's mascot, a green cartoon owl named Duo, has been a subject of an Internet meme in which the mascot will stalk and threaten users if they do not keep using the app.[63] Acknowledging the meme, Duolingo released a video on April 1, 2019 as an April Fools' Day joke; the video depicts a fictitious new premium feature called "Duolingo Push". According to the video, users of "Duolingo Push" will receive reminders to use the app in person by Duo himself, who stares at users and follows them around until they use the app (in the video, Duo is depicted by a person in a large mascot costume.)[64][65]

In November 2019, Saturday Night Live parodied Duolingo in a skit where adults learned to communicate with children using a fictitious course on the app titled "Duolingo for Talking to Children".[66]

Recognition and awards

Recognition and awards for the app

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] Duolingo won Best Education Startup at the 2014 Crunchies,[48] 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]

Recognition and awards for the company

Duolingo was named No. 44 on Fast Company's "The World's 50 Most Innovative Companies" list in 2018 "for making new languages irresistible".[70] No. 2 on Fast Company's "The World's Most Innovative Companies: Education Honorees" in 2018 "for making a new language irresistible",[71] and No. 2 on Fast Company's "The World's Most Innovative Companies: Education Honorees" in 2017 "for letting friends compare notes as they learn a new language".[72] No. 6 on Fast Company's "The World's Most Innovative Companies: Social Media Honorees" in 2017 "for letting friends compare notes".[73] No. 7 on Fast Company's "The World's Most Innovative Companies: Education Honorees" in 2013 "for crowdsourcing web translation by turning it into a free language-learning program".[74]

Duolingo won Inc. magazine's Best Workplaces 2018,[75] Entrepreneur magazine's Top Company Culture List 2018,[76] and appeared in CNBC's 2018 and 2019 "Disruptor 50" lists.[77][78][79] TIME Magazine's 50 Genius Companies.[80] In 2019, Duolingo was named one of Forbes's "Next Billion-Dollar Startups 2019".[81]

Features

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.[82]

Leaderboards

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.[83] In May 2019, Duolingo Clubs was replaced by Duolingo Leaderboards, of which there are ten: Bronze, Silver, Gold, Sapphire, Ruby, Emerald, Amethyst, Pearl, Obsidian and Diamond, in that increasing order. To get to the next league, the user has to rank in the top 10 out of 50 in a weekly XP race. Anyone in the bottom 5 out of 50 in the weekly race is demoted to the previous league.

Use in schools

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.[84] 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.[85]

Effectiveness

Duolingo has received criticism for its lack of effectiveness in helping students to learn a language. Luis von Ahn "promises only to get users to a level between advanced beginner and early intermediate." After six months of studying French with Duolingo, von Ahn demonstrated a lack of basic verb tenses when asked to describe his weekend in French, "mangling his tenses." Bob Meese, Duolingo's chief revenue office, did not understand the spoken question “¿Hablas español?” after six months of Duolingo Spanish study.[1]

Language courses

Courses for English speakers

As of 12 December 2019, 35 courses are available to the public in English, three of which are constructed languages, and those three include two fictional languages.[86][87][88] In this list, the courses are ordered by number of active learners.

Complete
Beta
Alpha

As of 12 December 2019, three courses for English speakers are in development (ordered by progression percentage towards completion according to the Weekly Incubator Update[95])

Release dates of English courses

Number of speakers
(in 1000s) 		Teaching Release date
23,900 Spanish 30 November 2011
7,730 German 30 November 2011
13,500 French 19 June 2012
2,230 Portuguese 30 October 2012
5,240 Italian 13 November 2012
1,350 Dutch 16 July 2014
508 Danish 25 August 2014
934 Irish 25 August 2014
1,190 Swedish 17 November 2014
1,450 Turkish 23 March 2015
311 Ukrainian 21 May 2015
842 Norwegian 21 May 2015
289 Esperanto 28 May 2015
3,270 Russian 2 November 2015
875 Polish 10 December 2015
382 Welsh 26 January 2016
586 Vietnamese 21 April 2016
823 Hebrew 21 June 2016
317 Hungarian 30 June 2016
1,050 Greek 30 August 2016
443 Romanian 15 November 2016
362 Swahili 20 February 2017
6,250 Japanese 18 May 2017
952 High Valyrian 12 July 2017
417 Czech 5 September 2017
3,660 Korean 10 October 2017
3,520 Chinese 15 November 2017
368 Klingon 15 March 2018
1,050 Hindi 18 July 2018
382 Indonesian 15 August 2018
560 Hawaiian 5 October 2018
306 Navajo 5 October 2018
1,190 Arabic 25 June 2019
552 Latin 28 August 2019
102 Scottish Gaelic 26 November 2019

Courses unavailable in English

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

Courses available in other languages

As of 28 August 2019, the following languages are available to speakers of languages other than English:[99]

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

Number of languages available for speakers of 'x' language on the app and on the website

Rank
Number of languages
available for speakers of:		 On app On website
1 English 35 38 (Finnish, Haitian Creole, and Yiddish in the incubator)
2 Spanish 10 10
3 Chinese 6 7 (German in incubator)
4 Portuguese 6 6
5 French 5 5
6 Arabic 4 5 (Spanish in incubator)
7 Russian 4 5 (Swedish in incubator)
8 Turkish 3 5 (French and Swedish in incubator)
9 Italian 3 (Spanish not available on app) 4
10 German 3 3
11 Japanese 2 2
12 Dutch 1 2 (German in incubator)
13 Czech 1 1
14 Greek 1 1
15 Hindi 1 1
16 Hungarian 1 1
17 Indonesian 1 1
18 Korean 1 1
19 Polish 1 1
20 Romanian 1 1
21 Thai 1 1
22 Ukrainian 1 1
23 Vietnamese 1 1
24 Bengali – 1 (English in incubator)
25 Punjabi (Gurmukhi) – 1 (English in incubator)
26 Tagalog – 1 (English in incubator)
27 Tamil – 1 (English in incubator)
28 Telugu – 1 (English in incubator)

List of courses by number of learners

As of December 2019, 94 courses are available to start learning, and 10 are available to be notified when they are released.[109]

Rank Teaching For Speakers of Number of Learners Release date[110]
1 English Spanish 27,300,000[111] 2012/03/30 - 30 March 2012
2 Spanish English 24,000,000[112] 2011/11/30 - 30 November 2011
3 French English 13,500,000[113] 2012/06/19 - 19 June 2012
4 English Portuguese 10,600,000[114] 2012/10/30 - 30 October 2012
5 German English 7,760,000[115] 2011/11/30 - 30 November 2011
6 Japanese English 6,330,000[116] 2017/05/18 - 18 May 2017
7 English Russian 5,670,000[117] 2015/11/02 - 2 November 2015
8 Italian English 5,250,000[118] 2012/11/13 - 13 November 2012
9 English Arabic 4,490,000[119] 2014/05/09 - 9 May 2014
10 English French 4,380,000[120] 2013/05/07 - 7 May 2013
11 French Spanish 3,880,000[121] 2014/01/10 - 10 January 2014
12 Korean English 3,670,000[122] 2017/10/10 - 10 October 2017
13 Chinese English 3,540,000[123] 2017/11/15 - 15 November 2017
14 Russian English 3,270,000[124] 2015/11/02 - 2 November 2015
16 English Chinese 3,070,000[125] 2014/04/11 - 11 April 2014
15 English Turkish 3,040,000[126] 2013/12/29 - 29 December 2013
17 Spanish Portuguese 2,630,000[127] 2014/03/09 - 9 March 2014
18 Italian Spanish 2,480,000[128] 2014/09/15 - 15 September 2014
19 English German 2,280,000[129] 2013/11/27 - 27 November 2013
20 Portuguese English 2,230,000[130] 2012/10/30 - 30 October 2012
21 English Vietnamese 2,220,000[131] 2014/06/10 - 10 June 2014
22 English Italian 2,120,000[132] 2012/11/24 - 24 November 2012
23 Portuguese Spanish 2,090,000[133] 2014/02/01 - 1 February 2014
24 English Polish 1,660,000[134] 2014/01/19 - 19 January 2014
25 German Spanish 1,590,000[135] 2014/05/19 - 19 May 2014
26 English Hindi 1,570,000[136] 2014/04/21 - 21 April 2014
27 Turkish English 1,440,000[137] 2013/12/29 - 29 December 2013
28 Spanish French 1,420,000[138] 2014/05/21 - 21 May 2014
29 French Portuguese 1,400,000[139] 2015/03/12 - 12 March 2015
30 Dutch English 1,340,000[140] 2014/07/16 - 16 July 2014
31 Arabic English 1,200,000[141] 2019/06/25 - 25 June 2019
32 Swedish English 1,190,000[142] 2014/11/17 - 17 November 2014
33 English Japanese 1,150,000[143] 2014/03/03 - 3 March 2014
34 English Indonesian 1,130,000[144] 2014/04/23 - 23 April 2014
35 Spanish German 1,080,000[145] 2015/09/01 - 1 September 2015
36 Greek English 1,050,000[146] 2016/08/30 - 30 August 2016
37 Hindi English 1,050,000[147] 2018/07/18 - 18 July 2018
38 English Romanian 948,000[148] 2014/02/04 - 4 February 2014
39 Irish English 934,000[149] 2014/08/25 - 25 August 2014
40 High Valyrian English 919,000[150] 2017/07/12 - 12 July 2017
41 German Russian 887,000[151] 2014/03/26 - 26 March 2014
42 English Dutch 878,000[152] 2013/12/23 - 23 December 2013
43 Polish English 875,000[153] 2015/12/10 - 10 December 2015
44 Norwegian English 842,000[154] 2015/05/21 - 21 May 2015
45 Hebrew English 823,000[155] 2016/06/21 - 21 June 2016
46 English Czech 792,000[156] 2014/10/17 - 17 October 2014
47 Japanese Chinese 765,000[157] 2019/04/24 - 24 April 2019
48 Italian Portuguese 758,000[158] 2017/06/13 - 13 June 2017
49 French Arabic 756,000[159] 2016/02/02 - 2 February 2016
50 French German 749,000[160] 2014/03/31 - 31 March 2014
51 English Hungarian 715,000[161] 2014/01/08 - 8 January 2014
52 Russian Spanish 712,000[162] 2018/06/20 - 20 June 2018
53 Catalan Spanish 688,000[163] 2015/11/19 - 19 November 2015
54 German Portuguese 673,000[164] 2015/09/15 - 15 September 2015
55 English Korean 662,000[165] 2014/05/26 - 26 May 2014
56 French Russian 624,000[166] 2016/02/18 - 18 February 2016
57 Vietnamese English 587,000[167] 2016/04/21 - 21 April 2016
58 Italian French 561,000[168] 2014/11/06 - 6 November 2014
59 Hawaiian English 560,000[169] 2018/10/05 - 5 October 2018
60 Latin English 557,000[170] 2019/08/28 - 28 August 2019
61 English Ukrainian 553,000[171] 2014/08/12 - 12 August 2014
63 German French 545,000[172] 2015/10/14 - 14 October 2015
64 Spanish Russian 545,000[173] 2016/03/02 - 2 March 2016
62 German Turkish 536,000[174] 2015/12/14 - 14 December 2015
65 Danish English 506,000[175] 2014/08/25 - 25 August 2014
66 Korean Chinese 451,000[176] 2019/04/24 - 24 April 2019
67 Romanian English 442,000[177] 2016/11/15 - 15 November 2016
68 Spanish Chinese 423,000[178] 2016/07/06 - 6 July 2016
69 Czech English 416,000[179] 2017/09/05 - 5 September 2017
70 German Arabic 392,000[180] 2016/03/07 - 7 March 2016
71 Welsh English 381,000[181] 2016/01/26 - 26 January 2016
72 Indonesian English 381,000[182] 2018/08/15 - 15 August 2018
73 Klingon English 366,000[183] 2018/03/15 - 15 March 2018
74 French Italian 364,000[184] 2015/10/08 - 8 October 2015
75 Swahili English 361,000[185] 2017/02/20 - 20 February 2017
76 English Thai 332,000[186] 2017/05/10 - 10 May 2017
77 German Italian 317,000[187] 2017/01/09 - 9 January 2017
78 Hungarian English 317,000[188] 2016/06/30 - 30 June 2016
79 Ukrainian English 310,000[189] 2015/05/21 - 21 May 2015
80 Navajo English 304,000[190] 2018/10/05 - 5 October 2018
81 Russian Turkish 294,000[191] 2018/02/08 - 8 February 2018
82 Esperanto English 288,000[192] 2015/05/28 - 28 May 2015
83 Portuguese French 278,000[193] 2017/01/30 - 30 January 2017
84 Esperanto Spanish 266,000[194] 2016/10/26 - 26 October 2016
85 Guarani Spanish 259,000[195] 2016/08/30 - 30 August 2016
86 English Greek 257,000[196] 2014/04/25 - 25 April 2014
87 Esperanto Portuguese 224,000[197] 2018/05/15 - 15 May 2018
88 French Chinese 196,000[198] 2019/04/24 - 24 April 2019
89 Swedish Arabic 150,000[199] 2016/03/01 - 1 March 2016
90 Scottish Gaelic English 105,000[200] 2019/11/27 - 27 November 2019
91 Italian Chinese 71,000[201] 2019/04/24 - 24 April 2019
92 Spanish Italian 69,000[202] 2018/08/22 - 22 August 2018
93 Chinese Japanese 29,000[203] 2019/11/21 - 21 November 2019
94 Swedish Spanish 12,500[204] 2019/11/30 - 30 November 2019
95 Swedish Russian 85% complete, not released, estimated 29 September 2020[205]
97 English Tamil 79% complete, not released, estimated 31 December 2019[206]
96 English Bengali 72% complete, not released, estimated 25 February 2020[207]
98 French Turkish 68% complete, not released, estimated 14 September 2021[208]
99 Spanish Arabic 66% complete, not released, estimated 1 September 2019[209]
100 German Chinese 51% complete, not released, estimated 30 June 2020[210]
101 German Dutch 48% complete, not released, estimated 24 December 2019[211]
102 English Tagalog 40% complete, not released, estimated 1 September 2020[212]
103 English Punjabi (Gurmukhi) 26% complete, not released, estimated 8 July 2019[213]
104 English Telugu 21% complete, not released, estimated 25 December 2019[214]

List of courses in beta

As of 10 December 2019, 7 courses are in the beta phase on Duolingo.[215] Date courses started development were obtained from the Duolingo Wiki.[216] Release dates into Beta for Latin, Klingon, Hungarian, Navajo, and Esperanto for Portuguese were obtained from the Duolingo Wiki.[217] https://duolingo.fandom.com/wiki/. Chinese for Japanese release date was from a Reddit post,[218] and the Swedish for Spanish was obtained from the Duolingo forums.[219]

Rank Teaching For Speakers of Number of Learners Date courses started development Release date into Beta
1 Latin English 557,000[220] 2019-01-25 - 25 January 2019 2019/08/27 - 28 August 2019
2 Klingon English 366,000[221] 2015-04-09 - 9 April 2015 2018/03/15 - 15 March 2018
3 Hungarian English 317,000[222] 2014-03-12 - 12 March 2014 2016/06/30 - 30 June 2016
4 Navajo English 304,000[223] 2018-08-23 - 23 August 2018 2018/10/05 - 5 October 2018
5 Esperanto Portuguese 224,000[224] 2017-03-13 - 13 March 2017 2018/05/15 - 15 May 2018
6 Chinese Japanese 30,000[225] 2019-07-30 - 30 July 2019 2019/11/21 - 21 November 2019
7 Swedish Spanish 12,500[226] 2019-01-11 - 11 January 2019 2019/11/30 - 30 November 2019

List of courses being created

As of December 2019, 15 courses are currently being developed on Duolingo.[227] Percentages are based on jrikhal's Weekly Incubator Summary.[228]

Rank by

Estimated

Completion

Teaching For

Speakers of

Percent

completed

Date courses started

development [229]

Estimated

completion date

Number of Contributors
1 English Bengali 80% 2016/06/02 - 6 June 2016 2020/02/25 - 25 February 2020[230] 3[231]
2 English Tamil 79% 2016/06/01 - 1 June 2016 2019/12/31 - 31 December 2019[232] 2[233]
3 Swedish Russian 66% 2015/02/18 - 18 February 2015 2020/10/20 - 20 October 2020[234] 0[235]
4 English Tagalog 49% 2016/08/30 - 30 August 2016 2020/09/01 - 1 September 2020[236] 2[237]
5 German Dutch 45% 2019/06/18 - 18 June 2019 2019/12/24 - 24 December 2019[238] 6[239]
8 Yiddish English 34% 2015/02/19 - 19 February 2015 2020/12/31 - 31 December 2020[240] 7[241]
7 Spanish Arabic 30% 2016/09/12 - 12 September 2016 2021/12/31 - 31 December 2021 3[242]
8 English Punjabi (Gurmakhi) 29% 2016/12/08 - 8 December 2016 2019/7/8 - 8 July 2019[243] 3[244]
9 French Turkish 28% 2015/10/27 - 27 October 2015 2021/10/05 - 5 October 2021[245] 2[246]
10 English Telugu 21% 2016/08/10 - 10 August 2016 2019/12/25 - 25 December 2019[247] 3[248]
11 Haitian Creole English 6% 2017/01/27 - 27 January 2017 2020/12/31 - 31 December 2020[249] 2[250]
12 Finnish English 2% 2019/04/17 - 17 April 2019 2020/4/1 - 1 April 2020[251] 8[252]
13 Swedish Turkish 0% 2019/03/03 - 3 March 2019 2020/7/31 - 31 July 2020[253] 0[254]
14 German Chinese 0% 2018/09/10 - 10 September 2018 2020/6/30 - 30 June 2020[255] 0[256]
15 English Hebrew 0% 2019/11/03 - 3 November 2019 2019/12/15 - 15 December 2019[257] 0[258]

See also

References

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  2. ^ "We're thankful for our 200+ employees who have come from all around the world to help make education more accessible". Retrieved 27 December 2019.
  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. ^ "Duolingo". Ranking. Alexa Internet. Retrieved 23 December 2019.
  7. ^ "Duolingo moving to East Liberty, plans to add employees". The Business Journals. Retrieved 24 March 2016.
  8. ^ "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.
  9. ^ "Duolingo – Learn Languages for Free". Windows phone. Microsoft. Retrieved 21 November 2014.
  10. ^ Guliani, Parul. "Duolingo Looks To Dominate The Mobile Education Market With New Flashcard App TinyCards". Forbes. Retrieved 17 February 2017.
  11. ^ Siegler, MG (12 April 2011). "Meet Duolingo, Google's Next Acquisition Target; Learn A Language, Help The Web". TechCrunch. Retrieved 21 November 2014.
  12. ^ "The Duolingo Team". Twitpic.
  13. ^ "When Duolingo was young: the early years". VatorNews. 22 June 2018. Retrieved 21 December 2019.
  14. ^ 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.
  15. ^ "Immersion". duolingo. Archived from the original on 30 March 2019.
  16. ^ Olson, Parmy. "Crowdsourcing Capitalists: How Duolingo's Founders Offered Free Education To Millions". Forbes.
  17. ^ "Online Education as a Vehicle for Human Computation". National Science Foundation.
  18. ^ "Learn a language, translate the web". New Scientist.
  19. ^ Todd, Deborah M. (3 July 2012). "Ashton Kutcher backs CMU duo's startup Duolingo". Pittsburgh Post Gazette. Retrieved 13 July 2012.
  20. ^ "The Daily Start-Up: Kutcher-Backed Language Site Duolingo Finds Its Voice". The Wall Street Journal. 19 June 2012. Retrieved 13 July 2012.
  21. ^ "Series A - Duolingo - 2011-10-19". Crunchbase. Retrieved 13 December 2019.
  22. ^ Adi Robertson (16 December 2011). "Duolingo will translate the internet while teaching languages". The Verge. Retrieved 3 February 2016.
  23. ^ "We have a blog!". Official Duolingo Blog. Retrieved 14 December 2019.
  24. ^ "When Duolingo was young: the early years". VatorNews. 22 June 2018. Retrieved 21 December 2019.
  25. ^ "When Duolingo was young: the early years". VatorNews. 22 June 2018. Retrieved 14 December 2019.
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External links

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