In this interview, Severin Hacker, the co-founder and CTO of Duolingo, discusses Duolingo's shift to becoming an AI-first company, detailing how AI is used for content generation, creating new features like the "Video Call with Lily," and improving overall productivity. He shares insights on AI's strengths and limitations in software engineering, the future of education with personalized learning experiences, and the importance of motivation and engagement in language learning. Severin also touches on Duolingo's marketing strategies, the challenges of fundraising, and his perspective on Europe's role in the tech industry, as well as offering advice to founders and reflecting on his journey with Duolingo.