Senior Staff Machine Learning Systems Engineer, Feed Relevance

The Feed Relevance team is responsible for the end-to-end systems that power personalization and ranking for the main Reddit feeds. We prioritize building scalable, extensible, and highly performant personalization systems to improve the user experience and drive key business metrics.

What You’ll Do

As a Senior Staff Machine Learning Systems Engineer, you will help define and lead the vision for the systems that power the Reddit Home Feed. While this role sits within the Feed Relevance team, it is primarily a systems architecture and backend engineering position rather than a modeling role. We are looking for a distributed systems expert to own the 'engines' of personalization—the real-time serving pipelines, low-latency candidate retrieval systems, and high-throughput data fetching layers that allow our models to impact millions of users in milliseconds.

• Architect High-Performance Retrieval: Partner with platform teams to design and implement flexible, ultra-low-latency candidate retrieval solutions that balance discovery with computational efficiency.
• Optimize the Serving Lifecycle: Design and build "contributor-friendly" serving pipelines that allow backend and product engineers to safely inject logic and features without needing deep ML expertise.
• Build Predictive Reliability: Lead the development of sophisticated shadow-testing infrastructure to evaluate distribution shifts and system performance at scale before code ever hits production.
• Drive Cross-Stack Integration: Collaborate across t