Senior Staff Machine Learning Engineer, ML Understanding

About Reddit

Reddit is a community of communities, built on shared interests, passion, and trust. It's the internet's most authentic conversation space, hosting over 100,000 active communities and serving approximately 126 million daily active unique visitors. Learn more at www.redditinc.com.

About the Role

We are seeking a Senior Staff Machine Learning Engineer to lead Reddit’s next-generation user understanding initiative. Your primary goal will be to build a unified, high-fidelity representation of each user, powering personalization across the platform. This role demands deep expertise in mainstream ML user modeling and the ability to innovate using GenAI and LLMs for enhanced fidelity, adaptability, and expressiveness.

What You'll Do

• Design User Understanding Strategy: Define a comprehensive user understanding framework and strategy, dictating how users are represented, computed, stored, and exposed. Provide thought leadership in user modeling and set a long-term technical vision.
• Build Foundational User Models: Lead the design and implementation of advanced user models, such as large-scale user representation learning, to enhance personalization across key products like Feeds, Notifications, Search, and Ads.
• Reimagine User Understanding with LLM/GenAI: Evolve user modeling by leveraging LLMs for richer user understanding, exploring dynamic profiles, intent inference, and semantic reasoning over user behavior.
• Ship Large Scale User Understanding as a System: Partner with platform teams to design and build core components for large-scale learning and serving, ensuring scalability, reliability, and integration with MLOps systems.
• Drive Cross-Team Integration & Impact: Collaborate with product, infrastructure, and downstream ML teams to drive adoption of new user understanding models and ensure measurable end-to-end impact.
• Set Technical Bar & Mentor: Mentor senior engineers, lead design reviews, and champion engineering best practices within the user understanding domain.

Who You Might Be

• 10+ years of experience building and scaling production-grade ML systems, especially in user modeling, representation learning, or recommender systems.
• Proven track record of driving high-impact initiatives from concept to production.
• Product- and impact-oriented, focused on moving real-world metrics.
• Strong fundamentals in mainstream user understanding ML approaches and their real-world trade-offs.
• Excited about GenAI and experienced in applying LLMs or foundation models for significant system evolution.
• Systems-thinking approach, considering the entire lifecycle from data to serving.
• Strong influence and collaboration skills across product, infra, and ML teams.
• Mentorship experience and a commitment to raising the technical bar.
• Comfort navigating trade-offs in large-scale, user-facing systems.

Benefits

• Comprehensive Healthcare Benefits and Income Replacement Programs
• 401k with Employer Match
• Global Benefit programs (workspace, professional development, caregiving support)
• Family Planning Support
• Gender-Affirming Care
• Mental Health & Coaching Benefits
• Flexible Vacation & Paid Volunteer Time Off
• Generous Paid Parental Leave

Pay Transparency

• This job posting may span more than one career level.
• Eligible for equity in the form of restricted stock units and potentially commission.
• U.S. benefits include medical, dental, vision insurance, 401(k) with employer match, generous time off, and parental leave.
• Base salary range: $266,000 - $372,400 USD.
• Final offer amounts depend on skills, experience, and other factors.