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

Location: San José, San José Province, cr, Remote

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.

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