Senior Staff Machine Learning Systems Engineer, Feed Relevance

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

The Feed Relevance team is responsible for the end-to-end systems that power personalization and ranking for Reddit's main feeds. We focus on building scalable, extensible, and highly performant systems to enhance user experience and drive key business metrics. As a Senior Staff Machine Learning Systems Engineer, you will define and lead the vision for the systems powering the Reddit Home Feed. This is primarily a systems architecture and backend engineering role, focusing on the real-time serving pipelines, low-latency candidate retrieval, and high-throughput data fetching that enable our models to operate effectively.

What You’ll Do

• Architect High-Performance Retrieval: Design and implement ultra-low-latency candidate retrieval solutions that balance discovery with computational efficiency.
• Optimize the Serving Lifecycle: Build "contributor-friendly" serving pipelines that allow backend and product engineers to safely inject logic and features.
• Build Predictive Reliability: Lead the development of sophisticated shadow-testing infrastructure to evaluate system performance at scale before production deployment.
• Drive Cross-Stack Integration: Collaborate across the stack, from GraphQL to upstream infrastructure, to ensure a resilient, maintainable, and extensible feed architecture.
• Performance Engineering: Identify and resolve bottlenecks within the feed's ecosystem to improve user experience.

Qualifications

• 10+ years of experience in backend software engineering, specializing in architecting and scaling high-throughput, low-latency distributed systems for personalization or recommendation engines.
• Expert-level understanding of distributed systems, including real-time data pipelines, advanced caching strategies, and storage layer optimization.
• Proven ability to lead technical strategy across organizational boundaries, collaborating with Infrastructure and Platform teams.
• Adept at navigating complex system trade-offs, balancing resilience, latency, and evolving ML model needs.
• Strong communicator and mentor with experience influencing best practices across a large engineering organization.

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.