Duolingo, Inc. is an American educational technology company that produces learning apps and provides language certification. Duolingo offers courses on 42 languages, ranging from English, French, and Spanish to less commonly studied languages such as Hawaiian, Māori, and Navajo, and even constructed languages such as Esperanto and Klingon. It also offers courses on music, math, and chess. The learning method incorporates gamification to motivate users with points, rewards and interactive lessons featuring spaced repetition. The app promotes short, daily lessons for consistent, phased practice.
Duolingo also offers the Duolingo English Test, an online language assessment, and Duolingo ABC, a literacy app designed for children. The company follows a freemium model, where some content is provided for free with advertising, and users can pay for ad-free services which provide additional features.
History Early history The idea of Duolingo was formulated in 2009 by Carnegie Mellon University professor Luis von Ahn and his Swiss-born post-graduate student Severin Hacker. Von Ahn had sold his second company, reCAPTCHA, to Google and, with Hacker, wanted to work on an education-related project. Von Ahn stated that he saw how expensive it was for people in his community in Guatemala to learn English. Hacker (co-founder and current CTO of Duolingo) believed that "free education will really change the world" and wanted to provide an accessible means for doing so. He was recognized by the National Inventors Hall of Fame for his contributions to language learning and technological development. The Duo mascot is a green owl because co-founder Severin Hacker hates the color green.
The project was originally financed by von Ahn's MacArthur fellowship and a National Science Foundation grant. The founders considered creating Duolingo as a nonprofit organization, but von Ahn judged this model unsustainable. Its early revenue stream, a crowdsourced translation service, was replaced by a Duolingo English Test certification program, advertising, and subscription.
Funds
In October 2011, Duolingo announced that it had raised $3.3 million from a Series A round of funding, led by Union Square Ventures, with participation from author Tim Ferriss and actor Ashton Kutcher's investing firm A-Grade Investments. Duolingo launched a private beta on November 30, 2011, and accumulated a waiting list of more than 100,000 people by December 13. It launched to the general public on June 19, 2012, at which point the waiting list had grown to around 500,000.
In September 2012, Duolingo announced that it had raised a further $15 million from a Series B funding round led by New Enterprise Associates, with participation from Union Square Ventures. In November 2012, Duolingo released an iPhone app, followed by an Android app in May 2013, at which time Duolingo had around 3 million users. By July 2013, it had grown to 5 million users and was rated the No. 1 free education app in the Google Play Store.
In February 2014, Duolingo announced that it had raised $20 million from a Series C funding round led by Kleiner Caufield & Byers, with prior investors also participating. At this time, it had 34 employees, and reported about 25 million registered users and 12.5 million active users; it later reported a figure closer to 60 million users.
In June 2015, Duolingo announced that it had raised $45 million from a Series D funding round led by Google Capital, bringing its total funding to $83.3 million. The round valued the company at around $470 million, with 100 million registered users globally. In April 2016, it was reported that Duolingo had more than 18 million monthly users..
In July 2017, Duolingo announced that it had raised $25 million in a Series E funding round led by Drive Capital, bringing its total funding to $108.3 million. The round valued Duolingo at $700 million, and the company reported passing 200 million registered users, with 25 million active users. It was reported that Duolingo had 95 employees. Funds from the Series E round would be directed toward creating initiatives such as a related educational flashcard app, TinyCards, and testbeds for initiatives related to reading and listening comprehension. On August 1, 2018, Duolingo surpassed 300 million registered users.
In December 2019, it was announced that Duolingo raised $30 million in a Series F funding round from Alphabet's investment company, CapitalG. The round valued Duolingo at $1.5 billion. Duolingo reported 30 million active users at this time. The headcount at the company had increased to around two hundred, and new offices had been opened in Seattle, New York, and Beijing. Duolingo planned to use the funds to develop new products and further expand its team in sectors like engineering, business development, design, curriculum and content creators, community outreach, and marketing.
Features and media
In October 2013, Duolingo launched a crowdsourced language incubator. Initially relying on volunteers developing its courses, in March 2021 Duolingo announced that it would be ending its volunteer contributor program. The company said that language courses would instead be maintained and developed by professional linguists aligning with CEFR standards. On June 28, 2021, Duolingo filed for an initial public offering on NASDAQ under the ticker DUOL. From August 2021 to June 2022, the Duolingo language learning app was removed from some app stores in China. In March 2022, Duolingo discontinued its community forums.
In August 2022, Duolingo overhauled its interface, changing its course structure from a tree-like design, where users could choose from a range of lessons after completing previous ones, to a linear progression. This update has been criticized by users across social media outlets, such as Reddit and X (formerly Twitter). CEO Luis von Ahn stated that there were no plans to reverse the changes.
In October 2022, Duolingo acquired Detroit-based animation studio Gunner, a long-time design and animation partner that had produced graphics and animations for Duolingo, Duolingo ABC, and the company's marketing campaigns.
In March 2023, Duolingo officially announced the planned Duolingo Max, a subscription tier above Super Duolingo, in their blog. In October 2023, Duolingo released math and music courses in English and Spanish for iOS users.
In January 2024, Duolingo fired around ten percent of its contract workforce and announced plans to replace them with AI. The company acquired Detroit-based design studio Hobbes in March.
Duolingo announced plans to expand its music education offerings after acquiring London-based NextBeat, a music and gaming start-up company.
Products and services Courses Language courses CEFR based language courses for learners of English, Spanish, French, Italian, Chinese (Mandarin), Japanese, Korean, Portuguese, and German are available for all users. Additional courses are also available for speakers of English (Arabic, Czech, Danish, Dutch, Esperanto, Finnish, Greek, Haitian Creole, Hawaiian, Hebrew, High Valyrian, Hindi, Hungarian, Indonesian, Irish, Klingon, Latin, Navajo, Norwegian, Polish, Romanian, Russian, Scottish Gaelic, Swahili, Swedish, Turkish, Ukrainian, Vietnamese, Welsh, Yiddish, Zulu), Chinese (Chinese (Cantonese)), Arabic (Swedish), and Spanish (Catalan, Russian, Swedish).
Subscriptions Super Duolingo As of 2014, most of Duolingo's language learning features are free with advertising. Users can remove advertising by paying a subscription fee or promoting referral links. The paid user program, Super Duolingo (formerly known as Duolingo Plus), offers unlimited retries and access to some additional types of lessons.
Duolingo Max Duolingo Max is a subscription above Super Duolingo that adds additional functions using generative AI: Roleplay, an AI conversation partner; and Video Call, where users can video chat with one of the characters, which currently includes only Lily. It is intended to provide immersion through conversation. Explain My Answer - a AI generated feature to help users understand their mistakes - used to be Max exclusive, but is now free for all users as of 2026.
Duolingo for Schools Duolingo for Schools is designed to help teachers use Duolingo in their classrooms. It allows teachers to create classrooms, assign lessons, track student progress, and personalize learning. However, Duolingo decided to sunset the program in 2027.
Duolingo English Test
The Duolingo English Test (DET) is an online English proficiency test that measures proficiency in reading, writing, speaking, and listening in English. It is a computer-based test scored on a scale of 10–160, with scores above 120 considered English proficiency. The test's questions algorithmically adjust to the test-takers' ability level.
Other programs Duolingo Math was an app course for learning elementary mathematics. It was announced on YouTube on August 27, 2022. It was merged into Duolingo in 2024, now available as a course.
On October 11, 2023, the company released Duolingo Music, a new platform within the existing app that provides basic music learning through piano and sheet music lessons.
Duolingo introduced chess lessons starting on April 22, 2025. The lessons gradually increasing in difficulty. In 2026, Duolingo launched a feature allowing players to play against each other, and as of early 2026 had seven million daily active users.
is a free app designed for young children to learn letters, their sounds, phonics, and other early reading concepts. Released in 2020, it does not contain ads or in-app purchases. As of April 2024, iOS and Android versions were available, but only in English.
Learning model Exercises and pacing On Duolingo, learners learn by doing, engaging with the course material. Lessons are designed to be brief, allowing users to learn in manageable chunks. Duolingo uses a gamified approach to learning, with lessons that incorporate translating, interactive exercises, quizzes, and stories. It also uses an algorithm that adapts to each learner and can provide personalized feedback and recommendations.
Gamification Duolingo provides a competitive space, such as in leagues, where people can compete with randomly selected groupings of up to 30 users. Leagues: Bronze, Silver, Gold, Sapphire, Ruby, Emerald, Amethyst, Pearl, Obsidian, Diamond. Rankings in leagues are determined by the number of experience points earned in a week. Badges in Duolingo represent achievements earned from completing specific objectives. Users can also create their own avatars and as of 2026 users can add seasonal suits to their avatars.
Any lesson completed in Duolingo will count towards the user's daily streak. The daily streak's visual symbol in the app is fire. Duolingo's "Friend Streak" lets users maintain streaks with up to five friends. Streaks encourage consistent daily practice and help build a habit of regular learning.
The app has a personalized bandit algorithm system (later the A/B tested variant recovering difference softmax algorithm) that determines the daily notification that will be sent out to the user.
Duolingo Score The Duolingo Score is an estimate of users' proficiency in the language they are learning in CEFR-aligned courses. The Duolingo Score provides a granular assessment of what a user has learned and what they can do with the language. As of June 2026, languages in the Duolingo app are represented with Duolingo Scores, though they are still shown in the website as aligned with the CEFR standards. The DET also uses a similar scoring system. Users can also display their Duolingo Scores to their LinkedIn profile in the event a job requires employees to be bilingual. The most developed CEFR-aligned courses (French, English, and Spanish) cover the Duolingo Score from 0 to 130.