Senior Fullstack Engineer (.NET + React)

About the role

Software Mind, a software engineering partner building digital products for US and European clients, is 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, and the engagement is a short, focused one: a discovery phase followed by two-week sprints through production release.

Key responsibilities

• 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, and 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

Required profile

• 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
• Clean architecture: dependency injection, DDD/CQRS concepts
• 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