Staff Machine Learning Engineer, Ranking and Personalization

Reddit is a community of communities and is seeking a Staff Machine Learning Engineer to build ranking and personalization systems. This role involves collaborating with cross-functional teams to design and ship innovative models that enhance user engagement and app discovery on the platform.

Responsibilities:

• Design and ship next-generation ranking and personalization models that power discovery of Dev Platform apps and games across Reddit surfaces
• Partner with ML, DS, and product to define signals, APIs, and feedback loops for building, deploying, and iterating on ranking models
• Explore and productionize new retrieval, ranking, and experimentation approaches that unlock new Dev Platform experiences
• Champion model quality, reproducibility, and experimentation best practices — including offline evaluation, A/B testing, and monitoring for model health and degradation
• Mentor engineers and lead technical discussions, shaping the long-term ranking and personalization modeling strategy for Dev Platform

Requirements:

• 8+ years of experience building and deploying ML models in production, particularly in ranking or personalization modeling, large-scale representation learning, or recommender systems
• Proven track record working on cross-functional product teams (PM, Design, DS, Eng) where you owned end-user outcomes, not just models or infra, and shipped features that moved core product metrics
• Strong domain knowledge in modern ranking and personalization techniques: user/item embeddings, multi-task learning, sequential modeling, or similar approaches applied at scale
• Experience designing and implementing performant, stable, and efficient ML or ranking systems (recommendation, ads, search, feed, or similar high-throughput decision systems)
• Strong organizational skills with the ability to prioritize, sequence, and de-risk work, keeping complex projects on schedule with a high attention to detail
• BS in Computer Science or a related technical field, or equivalent practical experience
• Comfortable with software engineering best practices: testing, code reviews, technical design docs, and clear documentation for other teams that depend on your systems
• Entrepreneurial mindset: you are self-directed, comfortable in ambiguity, and biased toward action in fast-paced environments. You like 0→1 building, iteration, and learning from experiments and failures
• Excellent communication skills: you collaborate effectively in a remote, cross-functional team, and can explain complex ML and ranking concepts to both technical and non-technical stakeholders
• Languages: Go, Python, C++ or any object oriented programming language
• Libraries: Baseplate, GraphQL
• Databases: Redis, Postgres, Memcached
• Tools: Kubernetes, AWS, Docker, GCP