Principal Full Stack Engineer, B2B eCommerce

Principal Full Stack Engineer, B2B eCommerce

Location: Boston, MA (Hybrid) 
Reports to: Team Lead, eCommerce
Role type: Full-time, individual contributor

About Fusion Worldwide
Fusion Worldwide is the preeminent open market distributor of electronic components and products. Founded in 2001 and headquartered in Portsmouth, NH, with offices and quality centers around the world, Fusion sources, inspects, tests and delivers components to OEMs, CMs and ODMs across a wide range of industries. Learn more at fusionww.com.

The Role
You will be a senior technical owner of Fusion's B2B eCommerce platform, which includes fusionww.com, our GraphQL and REST APIs, the internal admin portal, and the event pipeline behind them. You will design and ship customer-facing and internal commerce features end to end, run the services on Azure, and build AI agents that make our sales and operations teams faster. Our audience is entirely business buyers, including OEMs, CMs and ODMs. Even our smaller transactions are typically for business use, not personal consumption.

Our Palantir Foundry platform is the data layer behind customer intelligence and sales workflows. You will consume it through its APIs and SDKs rather than build inside it. Foundry engineers own the data, and you turn it into great commerce experiences.

We are an AI-first team. Claude Code is part of everyone's daily workflow, AI code review is required on every pull request, and Claude-powered agents run in production.

Expect your time to split roughly 80% application development, 10% AI agents and LLM features, and 10% infrastructure and DevOps.

What You'll Do

Commerce and platform development: 
•    Design and deliver features across the customer site (Next.js, React, TypeScript), the GraphQL backend (Python, FastAPI, Strawberry, SQLAlchemy), and REST services. 
•    Own core commerce flows such as search and discovery, catalog and pricing display, quoting and RFQ, cart and checkout, and order status.
•    Build internal tools in the admin portal (Next.js, tRPC, Zod) used by sales, marketing, operations and compliance.
•    Work across Azure SQL/SQL Server, Redis, Algolia, and event-driven processing with Celery and Azure Service Bus.
•    Integrate with HubSpot, Amplitude, Contentful and Fusion's ERP through its API layer.
•    Consume Foundry data (Ontology objects, OSDK, APIs) to power customer intelligence and sales workflows, and partner with the data team on contracts and requirements.
AI agents and LLM features: 
•    Build and improve production agents and LLM features on the Claude API, Claude Agent SDK and Model Context Protocol (MCP).
•    Manage cost, token usage and output quality, and add evals and guardrails so agent behavior can be trusted.
•    Use Claude Code as a primary development tool, with human judgment on every merge.
Infrastructure and DevOps: 
•    Operate and extend services on Azure: Container Apps and Jobs, Azure SQL, Front Door and WAF, Key Vault, Service Bus, API Management, Application Insights and Log Analytics.
•    Manage infrastructure as code with Terraform and CI/CD with GitHub Actions and Azure Container Registry across dev, test, pre-release and production, including an active/active second region.
•    Improve observability and alerting and troubleshoot production issues by tracing real data.
•    Apply secure-by-default engineering: Key Vault secrets, least privilege, safe error handling and dependency hygiene.
Engineering ownership: 
•    Write well-tested code at every layer and keep it passing in CI.
•    Own the quality of your own work: test and verify that your code meets requirements before release. This is a developer-level QA, not a QA function.
•    Serve as the technical expert for the eCommerce application and development team, as a hands-on individual contributor.
•    Triage and resolve user-reported issues and fix bugs across the customer site, admin portal, and APIs.
•    Make and document architecture decisions, favoring the existing platform over new parallel infrastructure.
•    Partner with business stakeholders to assess feasibility and shape requirements.
•    Document what you learn so the next engineer, and the next AI session, don't have to rediscover it.

What You Bring
Required: 
•    10+ years of professional software engineering experience, with significant time building or running B2B eCommerce or other commercial systems (catalog, pricing, quoting, orders, checkout, or ERP integration).
•    Expert-level relational database skills, including schema design, query tuning, and concurrency (SQL Server preferred).
•    Hands-on experience with Azure or an equivalent cloud, including containerized services and infrastructure as code with Terraform.
•    Experience building with LLMs or agents, and daily practical use of AI coding assistants such as Claude Code, with sound judgment about verifying their output.
•    Experience with Git and GitHub, GitHub Actions, Jira and Agile/Kanban delivery.
•    Clear written communication and the ability to explain tradeoffs to business stakeholders.
Nice to have: 
•    Distribution or marketplace commerce experience, especially with complex pricing, quoting, or inventory.
•    Experience with Algolia, HubSpot or event-driven architecture.
•    Electronic components or supply chain domain knowledge.

What Success Looks Like
•    First 30 days: Ship a production feature end to end and take ownership of a core commerce flow.
•    3 months: Lead a major commerce initiative and ship at least one production agent or AI feature.
•    12 months: Be the go-to technical owner for eCommerce architecture, with measurable gains in [conversion / quote cycle time / reliability].