Senior AI Research Engineer at Duolingo

Our mission at Duolingo is to develop the best education in the world and make it universally available. It’s a big mission, and that’s where you come in!

At Duolingo, you’ll join a team that cares about finding innovative solutions to complex technical problems, running countless experiments (300+ at a time!) with our massive user base to make data-driven decisions, and educating our users and employees alike. You’ll have limitless learning opportunities, mentorship and collaboration with world-class minds, and a variety of projects with large scopes — while doing work that’s both fun and meaningful.

Join our life-changing mission to develop education for our half a billion (and growing!) learners around the world.

About the role...

We are looking for a Senior AI Research Engineer to join our Duolingo Video Call team. The ideal candidate will have a proven track record as an AI research engineer, with experience across various machine learning techniques including large language models, speech models, benchmarking, and/or personalization. They will have experience at multiple levels of the ML stack, including feature engineering, developing training data, fine-tuning, reinforcement learning, quality evaluations, deployment, and monitoring. On the Video Call team, we’re building AI systems that support the core learning mission of Duolingo, improving the learning experience and helping our learners build healthy, productive habits. Given the wide array of AI domains, broad experience in AI/ML is highly desirable.

🧠 You will...

• Join a full-stack team of frontend, backend and other AI Research engineers, fostering a collaborative and innovative work environment.
• Contribute to the development and training of a variety of machine learning models, including large-scale neural networks, speech recognition, and text-to-speech systems.
• Collaborate with cross-functional teams to understand their needs, to align the models’ outputs with company objectives.
• Participate in and influence strategic product and business decision making with members of the Language Learning leadership group.
• Stay up-to-date with the latest developments in machine learning and apply this knowledge to drive advancements in our projects.
• Mentor team members, providing guidance and support in their professional development.
• Ensure the delivery of high-quality, scalable, and efficient machine learning solutions.

✅ You have...

• Proven experience as an AI research engineer, for example, in LLMs, multimodal modeling, speech, or related fields.
• Strong background in training and fine-tuning large models in an applied setting.
• Advanced degree in Computer Science, Engineering, or a related field with a focus on machine learning or artificial intelligence, or equivalent experience.
• Excellent leadership and communication skills, with the ability to lead and inspire a team.
• Technical depth sufficient to guide architecture and implementation trade‑offs, evolve quality standards, and mentor engineers on best practices.
• Deep understanding of machine learning concepts, frameworks, and best practices.

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