Senior Full Stack Engineer Jobs in Seattle, WA

We are seeking an experienced Senior Full Stack Engineer – Commerce AI with a strong background in full-stack engineering and applied AI/LLM systems to support the client's Commerce AI team. This role sits at the intersection of technical innovation and guest experience, helping shape the strategic direction of AI-powered commerce solutions.

The successful candidate will architect, build, and deploy AI-native applications that directly impact high-traffic booking flows, dynamic pricing models, and personalized guest experiences, blending deep traditional full-stack engineering with hands-on orchestration of Agentic AI systems using modern LLMs and integration frameworks.

This role is ideal for a highly autonomous, detail-oriented senior individual contributor who is comfortable driving complex system design, working across dual-cloud environments, and delivering AI solutions within a high-traffic, revenue-generating e-commerce environment.

• Design, build, and scale secure, AI-native applications that enhance the digital storefront, optimize revenue, and personalize the guest journey.
• Implement advanced Agentic AI workflows, integrating with leading LLMs (Gemini, OpenAI, Anthropic) to build autonomous systems for planning, dynamic merchandising, and guest support.
• Leverage the Model Context Protocol (MCP) framework to seamlessly and securely connect AI models with enterprise booking engines, CRM systems, and real-time operational data.
• Write clean, maintainable, high-performance code across the stack utilizing C# (.NET) for high-throughput backend microservices and SvelteKit for dynamic, accessible user interfaces.
• Architect and manage cloud infrastructure across Azure and GCP, ensuring optimal deployment, latency reduction, scaling, and cost efficiency of AI workloads in high-traffic e-commerce environments.
• Drive complex system design discussions, establish technical guardrails, and ensure strict adherence to data privacy, AI safety, and enterprise architecture standards.

• 8+ years of professional software engineering experience.
• 3+ years of dedicated experience building and scaling production-grade AI-native or LLM-powered applications.
• Deep expertise in C# and the .NET ecosystem for building enterprise-grade APIs and highly available microservices.
• Proven track record building interactive, performance-optimized e-commerce or consumer-facing web applications using SvelteKit (or advanced Svelte).
• Hands-on experience deploying and managing production workloads in both Microsoft Azure and Google Cloud Platform (GCP).
• Hands-on experience working with the Model Context Protocol (MCP) to build secure ecosystem integrations for LLMs.
• Demonstrated experience designing autonomous agents, multi-agent orchestrations, and complex tool-use (function calling) paradigms.
• Deep understanding of API integration, fine-tuning patterns, and Retrieval-Augmented Generation (RAG) using Gemini, OpenAI, and Anthropic models.
• Strong background in system design, specifically balancing trade-offs between latency, cost, and accuracy when integrating AI into revenue-generating e-commerce flows.
• Proven success as an individual contributor in fast-paced, agile environments.

Preferred

• Experience building complex, high-transaction e-commerce systems involving dynamic pricing, real-time inventory management, or high-scale loyalty programs (travel industry background is a strong plus).
• Experience building complex reasoning pipelines, semantic routing architectures, or custom retrieval logic to supply AI agents with enterprise business rules.
• Knowledge of LLM monitoring, evaluation, and observability tools.