Senior Fullstack Engineer (.NET + React)

Job Description We’re partnering with a leading US promotional products and e-commerce company to build a new shipping and delivery service for its white-label B2B commerce platform. The platform runs on Shopify Plus with a .NET microservices backend on AWS. The new service connects major shipping carriers, the storefront, and the existing order management systems. It’s a short, focused engagement: a discovery phase, then two-week sprints through production release. What you’ll do: Build and own the Shopify storefront integration (Admin API, webhooks, checkout integration points) Develop React interfaces, including admin and configuration tools Design and implement .NET 8 Web API endpoints and services Integrate third-party APIs behind clean adapter layers Work with event-driven messaging (SNS/SQS), including idempotent handling and retries Keep customer-facing flows fast and resilient Align API contracts with the client’s storefront partner Write unit, integration, and component tests Document APIs (OpenAPI) and integration flows in Confluence Take part in code reviews, sprint ceremonies, and technical sessions with the client Qualifications Must have: 5+ years of full-stack development with strong C# / .NET (ASP.NET Core, .NET 6+) and React (TypeScript) Hands-on Shopify integration: Admin API (GraphQL/REST), webhooks, checkout integration Solid REST API design with OpenAPI / Swagger Third-party API integration: authentication, rate limits, retries, error handling Working knowledge of AWS: Lambda, SQS/SNS, ECS Clean architecture: dependency injection, DDD/CQRS concepts Testing discipline across backend and frontend Docker and CI/CD Excellent written and spoken English for daily client interaction Nice to have: Shipping or carrier API experience Shopify Plus, Hydrogen, or headless commerce storefronts Admin UIs built with component libraries (Polaris, MUI, or similar) Retail, e-commerce, or promotional products domain knowledge Company Description Software Mind is a software engineering partner that builds and scales digital products for companies in the US and Europe. Our LATAM teams work directly with client engineering teams on complex, high-impact projects.