Duolingo

Duolingo (/ˌduːoʊˈlɪŋɡoʊ/ DOO-oh-LING-goh) is an American platform that includes a language-learning website and mobile 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.

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 Ahnbelieve 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] <sup id="cite_ref-23">[23] <sup id="cite_ref-24">[24]

On June 19, 2012, Duolingo later launched for the general public.<sup id="cite_ref-25">[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.<sup id="cite_ref-26">[26]

On 13 November 2012, Duolingo released their iOS app through the iTunes App Store.<sup id="cite_ref-TCiOS_27-0">[27]  The application is a free download and is compatible with most iPhone, iPod and iPad devices.<sup id="cite_ref-28">[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.<sup id="cite_ref-29">[29]

On June 19, 2013, one year after launching for the general public, Duolingo passed 4 million users, all through word of mouth, <sup id="cite_ref-:0_30-0">[30]  and on November 21, 2013, Duolingo reached 15 million users<sup id="cite_ref-:0_30-1">[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.<sup id="cite_ref-31">[31]  It was reported Duolingo had about 25 million registered users, 12.5 million active users, and 34 employees.<sup id="cite_ref-32">[32]  On June 2, 2014, Duolingo passed 30 million users<sup id="cite_ref-:0_30-2">[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.<sup id="cite_ref-33">[33] <sup id="cite_ref-34">[34] <sup id="cite_ref-35">[35]

In April 2016 it was reported that Duolingo had 17 million monthly users.<sup id="cite_ref-36">[36] <sup id="cite_ref-37">[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.<sup id="cite_ref-38">[38] <sup id="cite_ref-39">[39]  It was reported that Duolingo had 95 employees,<sup id="cite_ref-40">[40]  and the funds would be directed toward creating initiatives such as TinyCards and Duolingo Labs.<sup id="cite_ref-forbes.com_41-0">[41]

On August 1, 2018, it was reported Duolingo passed 300 million users.<sup id="cite_ref-42">[42]

On December 4, 2019, it was announced that Duolingo raised $30 million in a series F sixth-round of investment from [https://en.wikipedia.org/wiki/Alphabet_Inc. 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.<sup id="cite_ref-43">[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.<sup id="cite_ref-44">[44]

During 2019, Duolingo grew from 170 staff members<sup id="cite_ref-45">[45]  to 200 employees,<sup id="cite_ref-46">[46]  with headquarters in the Pittsburgh neighborhood of East Liberty,<sup id="cite_ref-duolingo.com_47-0">[47] <sup id="cite_ref-48">[48] <sup id="cite_ref-49">[49]  and offices in New York, Seattle and Beijing.<sup id="cite_ref-50">[50]  Of Duolingo’s 200 employees, 166 work in its East Liberty headquarters, 17 work in New York, 8 in Seattle and 8 in China.<sup id="cite_ref-51">[51]

Duolingo had a revenue of $1 million in 2016, $13 million in 2017,<sup id="cite_ref-52">[52]  $36 million in 2018,<sup id="cite_ref-53">[53]  and is projected to hit $86 million in 2019.<sup id="cite_ref-54">[54]