Hundreds of millions of customers discover products on Amazon through personalized recommendations. Our team builds and operates the recommendation engine serving every marketplace, every surface, and every outbound channel at billions of requests per day. We're looking for a Software Development Engineer to help push it forward. Our systems span real-time machine learning inference, AI-powered automated merchandising, content ranking, and large-scale personalization, all built for low-latency performance and resilience through the highest-traffic shopping events. You will work on meaningful problems at massive scale, collaborating with talented engineers and scientists to shape how customers discover products across Amazon. The team is entering a new phase, taking personalization to new marketplaces worldwide and moving to AI-driven merchandising automation. This role is central to delivering that shift. Key job responsibilities Design, implement, and operate features across distributed, latency-sensitive services, owning end-to-end delivery from design through production launch and operational readiness Contribute to system design discussions and architectural decisions, balancing tradeoffs in scalability, maintainability, and performance while integrating machine learning models and content rankers into the serving layer Write high-quality, peer-reviewed code and raise the engineering bar through code reviews, design feedback, and mentoring teammates on best practices Expand platform capabilities to new marketplaces worldwide, building configurable tooling and self-service integrations for partner teams Participate in on-call rotations, identify root causes of operational issues, and drive improvements that strengthen system resilience and reduce toil A day in the life You start the day reviewing results from experiments impacting hundreds of millions of shoppers. Your time splits between focused build work — shipping features, reviewing code, designing recommendation strategies with applied scientists — and cross-team collaboration with partner engineering teams, product managers, or marketing stakeholders integrating new content sources. You deploy to production frequently and validate with real-time dashboards. On-call weeks focus on operational health and system resilience. About the team We own the recommendation engine behind Amazon's merchandising personalization, serving every marketplace and channel. The team is growing and has engineers based in San Diego and Seattle, at a range of experience levels, focused on high-quality code, frequent experimentation, and continuous delivery. Our priorities include AI-powered campaign automation, worldwide expansion, and platform modernization. We ship often, review rigorously, and support each other's growth.