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|Founder(s)||Luis von Ahn, Severin Hacker|
|CEO||Luis von Ahn|
|Industry||Online education, Professional certification, Translation, Crowdsourcing|
|Services||Language courses, Duolingo English Test, Duolingo for Schools, Tinycards flashcard app|
|Alexa rank||793 (July 2017)|
|Launched||30 November 2011|
|Native client(s) on||Android, iOS, Windows Phone, Windows 10 Mobile|
|Written in||Python, Scala|
Duolingo ( DEW-oh-LING-goh) is a freemium language-learning platform that includes a language-learning website and app, as well as a digital language proficiency assessment exam. As of November 2016 , the language-learning website and app offer 68 different language courses across 23 languages, with 22 additional courses in development. The app has about 200 million registered users across the world.
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.
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". 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 .
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" 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. Additional funding was later received in the form of investments from Union Square Ventures and actor Ashton Kutcher's firm, A-Grade Investments.
Duolingo started its private beta on November 30, 2011, and accumulated a waiting list of more than 300,000 users. 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. Duolingo has 95 staff members, of whom many were Google employees, and operates from an office in the Pittsburgh neighborhood of East Liberty.
On November 13, 2012, Duolingo released their iOS app through the iTunes App Store. The application is a free download and is compatible with most iPhone, iPod and iPad devices. 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. As of 2017, the company had a total funding of USD $108.3 million. Duolingo received a fifth-round $25 million in July 2017 from Drive Capital, with the funds directed toward creating initiatives such as TinyCards and Duolingo Labs.
Duolingo has a freemium business model and it uses advertising in both its Android and iPhone apps. Duolingo courses include periodic advertisements which users can pay a subscription fee to remove. To earn money, Duolingo originally employed a crowd sourced business model, where the content came from organizations that pay Duolingo to translate it. This business model was later discontinued, after it was decided the industry was too competitive (price-wise) with other services like Gengo and rapidly advancing neural machine translation technology, and too distant from its core goals. In July 2014, Duolingo started a language certification service, Test Center, as a new business model. As of September 2017, 50% of Duolingo's revenue came from ads and 48% came from in-app purchases, with the remaining 2% derived from the Duolingo English test.
Catalan and Guarani are available as a second language for Spanish speakers. English is also available as a separate course for numerous other languages such as Dutch, Portuguese, Italian, and Russian.
Duolingo provides 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. Duolingo launched Duolingo Test Center on July 22, 2014, now known simply as the Duolingo English Test (DET). It is an online language certification test that can be taken from home. 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. After select users were invited to a closed beta test, Duolingo released the app for iOS devices on July 19, 2016, for desktop on March 2, 2017 and for Android on August 30, 2017.
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). The server backend is written in the programming language Python. A component called the Session Generator was rewritten in Scala by 2017. The frontend is written 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.
In 2013, Apple chose Duolingo as its iPhone App of the Year, the first time this honor had been awarded to an educational application. Also, Duolingo won Best Education Startup at the 2014 Crunchies, and was the most downloaded app in the Education category in Google Play in 2013 and 2014. In 2015, Duolingo was announced the 2015 award winner in Play & Learning category by Design to Improve Life.