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Reviewed and published by trentmaziarz, March 21, 2026. Discovered and drafted by our automated research pipeline.
Duolingo uses a large language model from OpenAI (GPT-4) to power live conversation practice inside its app. Learners can text-chat with AI characters in simulated real-world scenarios, or video-call an animated AI character named Lily who speaks and responds in real time. These features launched in 2023 and are available to paid subscribers.
Details
Launched March 14, 2023 as part of the Duolingo Max subscription tier ($29.99/month), Roleplay places learners in scenarios like ordering coffee or planning a trip, with the large language model generating dynamic character responses constrained by educational prompts. Video Call — announced September 24, 2024 — adds spoken voice interaction with Lily, an animated AI character who adjusts to the learner's skill level, pauses to simulate thinking, and retains memory of past conversations. The system expanded to Android and nine languages by 2025. Each conversation is unique because the AI generates responses on the fly rather than selecting from pre-written scripts.
Products affected
Duolingo Max
Sources & Evidence
Company Disclosure
Other practices by Duolingo
Customer SvcDuolingo uses an AI chatbot (powered by a company called Decagon) to handle the majority of customer support requests for the Duolingo English Test. The AI fully resolves about 80% of chat inquiries without any human involvement, answering questions about test registration, scores, and institutional acceptance.Data AnalysisDuolingo uses a machine learning model to decide, in real time, whether to show each individual user an advertisement, a subscription offer, or neither — predicting which choice is most likely to generate revenue from that specific person at that moment. The system was credited with generating tens of millions of dollars in additional annual revenue.Data AnalysisDuolingo uses a machine learning algorithm to decide which push notification to send each user, at what time, and how often — optimizing for the messages most likely to get a lapsed learner back into the app. The system was published as research in 2020 and was shown to increase the number of daily active users by 0.5% and improve retention of new users by 2%.
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