[8BE] Senior Fullstack Engineer (.NET + React)

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. 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 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 interactionNice 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