Backend Software Engineer, AI Platform

About the role

eBay is looking for a Backend Software Engineer to help evolve the Decisioning & Execution Engine (DEX) into an AI‑native decisioning platform. You will design, build, and maintain backend services that power real‑time and batch decision flows across multiple internal products.

Key responsibilities

• Design, implement, and maintain backend services and APIs for DEX decisioning.
• Integrate machine‑learning and LLM‑driven components (model inference, feature computation, policy orchestration) into existing rule flows.
• Collaborate with data scientists and rule analysts to productionize models, define interfaces, and safely deploy decision logic with A/B and canary rollouts.
• Extend the rules and configuration framework so policy teams can author, test, and deploy decisions without code changes.
• Partner with product and partner teams (Customer Support, Risk, Trust, Billing, Returns) to translate business policies into technical solutions.
• Participate in code reviews, architecture discussions, and on‑call duties for owned services.

Required profile

• Backend engineer with strong experience in a strongly typed language (e.g., C#, Java) and building distributed services in production.
• Comfortable working with SQL datastores, designing schemas, and writing performant queries for high‑volume flows.
• Experience with AI/ML in production, such as integrating models behind APIs or building inference services.
• Familiarity or eagerness to work with LLM‑based applications, prompt design, retrieval‑augmented workflows, and human‑in‑the‑loop feedback.
• Systems thinking mindset focused on latency, throughput, resilience, and impact of changes.
• Ability to collaborate closely with product managers, analysts, and operations teams.

Required skills

• C#
• Java
• SQL
• Python
• Model‑serving frameworks
• API development
• Distributed services
• A/B testing
• Canary rollouts
• LLM integration
• Prompt design
• Retrieval‑augmented workflows