Senior Staff Machine Learning Engineer (ML Understanding)

Join Reddit as a Senior Staff Machine Learning Engineer, where you will lead the development of a unified user understanding framework that powers personalization across the platform. You will design and implement advanced user models, reimagine user understanding with LLM/Gen-AI, and drive cross-team integration and impact. This high-impact role will shape the daily experience of hundreds of millions of users and advance personalization and relevance at a global scale.

• Definir un marco y una estrategia unificados para la comprensión del usuario, incluyendo cómo se representan y se computan.
• Liderar el diseño y la implementación de modelos de usuario avanzados, como el aprendizaje de representación de usuario a gran escala.
• Colaborar con equipos de producto para impulsar la experimentación y la adopción de nuevos modelos de comprensión del usuario.

• This role requires deep expertise in mainstream ML user modeling approaches (e.g., large-scale embeddings, user interest modeling, affinities, behavioral signals) and the ability to reimagine these systems in the GenAI era—leveraging LLMs and foundation models to unlock step-change improvements in fidelity, adaptability, and expressiveness
• You think in systems, not just models: you consider data, training, evaluation, serving, and adoption as a cohesive whole, and design with end-to-end impact in mind
• You influence beyond your immediate team: partnering effectively with product, infra, and other ML teams, and driving alignment across multiple stakeholders
• You are comfortable navigating trade-offs across quality, latency, cost, and safety, especially in large-scale, user-facing systems
• You raise the technical bar: mentoring senior engineers, leading design reviews, and establishing best practices for building reliable, scalable ML systems
• You bring strong fundamentals in mainstream user understanding ML approaches (e.g., representation learning, behavioral modeling, user clustering), and understand their trade-offs in real-world systems
• You have at least 10 years experience building and scaling production-grade ML systems, particularly in user modeling, large-scale representation learning, or recommender systems
• You have a track record of driving ambiguous, high-impact initiatives from concept to production, shaping both technical direction and execution
• You are product- and impact-oriented: you care deeply about how your work moves real metrics (e.g., engagement, retention, revenue), not just model quality
• You are excited about the GenAI shift and have experience (or strong intuition) applying LLMs or foundation models to evolve existing systems, going beyond incremental improvements