river - Senior/Staff Machine Learning Engineer

• Design, build, and iterate on machine learning models and LLM-based systems that power critical decisions across fraud, compliance, growth, and operations • Work with messy, real-world data to identify signals, build features, and continuously improve model performance • Make practical tradeoffs between model performance, interpretability, and operational cost • Partner closely with product and operations to identify and solve problems that directly impact experience of hundreds of thousands of clients • Contribute to backend systems and data pipelines that support model training and inference (without being primarily an infrastructure role) • Write high-quality, tested code and participate in code reviews • Take long-term ownership of critical systems as River scales • WHAT WE LOOK FOR IN YOU • 4+ years of experience building and applying machine learning models in real-world settings, or comparable research experience • Strong intuition for ML concepts and how they apply in practice (i.e., tradeoffs) • Experience working on problems involving noisy, imbalanced, or real-world data • You take ownership of systems and are comfortable solving ambiguous problems • You have strong judgment around correctness, reliability, and operational risk • You can translate between technical systems and business/product needs • You're excited about what we are building at River