Staff AI Research Engineer 

From Duolingo’s posting

... We are looking for an experienced AI Research Engineer to join our Duolingo Monetization team. The ideal candidate will have a proven track record as an AI research engineer, with extensive experience across various machine learning techniques including large language models, multi-armed bandits, and more. They will have experience at all levels of the ML stack, including feature engineering, developing training data, fine-tuning, reinforcement learning, quality evaluations, deployment, and monitoring. On the Monetization team, we’re building AI systems to improve the learning experience while driving our business, including deploying our research into bandit models to balance revenue and retention.