Preply, the world’s largest online language‑learning marketplace, pairs more than 100,000 tutors with students in over 180 countries. To cut repetitive admin work and give learners clearer progress signals, the company launched Lesson Insights, an AI layer built on the OpenAI API. After each one‑to‑one session the system parses the transcript and returns grammar, vocabulary and pronunciation feedback for both tutor and student.

The AI-generated report appears minutes before the lesson ends, delivering a concise summary, corrected sentences, highlighted vocab and next‑step recommendations directly in the chat thread. Tutors use the data to craft personalized homework, while 75% of English‑language learners and over 70% of tutors report regular use. Satisfaction scores hover at 4.7 out of 5 from more than 300,000 ratings.

Internally, Preply rolled out ChatGPT Enterprise to 600 employees across New York, Kyiv, London and Barcelona, lifting weekly active usage from 60% to 95%. Engineering teams rely on Codex, with 94% of developers using it for code generation and review, accelerating feature delivery. The combined human‑AI workflow has turned lessons into continuous, data‑driven learning journeys, significantly improving retention.