C# / .NET Developer (Shopify / Middleware Focus)

About DemandPDX DemandPDX is a Salesforce Crest (Gold) Partner and Shopify Plus Partner, recognized with the highest ratings for Salesforce Commerce Cloud on Salesforce AppExchange. With more than 450 eCommerce implementations delivered by our team, we bring deep expertise across architecture, development, strategy, QA, and project leadership. Our entire team is U.S.-based, and we pride ourselves on delivering high-end strategic guidance while integrating seamlessly as an extension of our clients’ teams. Why Work With DemandPDX We are committed to building a culture that values flexibility, excellence, and long-term career growth. For full-time employees, we offer: 35- or 40-hour work weeks 100% remote work Flexible schedules Competitive compensation Performance-based bonus opportunities Medical, dental, vision, and disability insurance (employee coverage provided) HSA plan options Simple IRA with 3% company match Company-paid life insurance Paid holidays and paid time off Paid maternity and paternity leave Paid bereavement and natural disaster leave Company-provided laptop Note: This role is structured as a contract engagement, with potential for conversion to full-time employment. Full benefits apply upon full-time conversion. Do you enjoy building scalable backend systems that power seamless digital experiences? Do you thrive in integration-heavy environments where performance, data flow, and reliability matter? Do you like working behind the scenes to ensure platforms talk to each other efficiently and securely? As a C# / .NET Developer, you will play a key role in expanding and supporting a client’s middleware layer that integrates Shopify and other systems. You may also contribute to a mobile app backend running in a Platform-as-a-Service (PaaS) environment, as the existing provider transitions off the account. This role requires strong backend engineering skills, experience with APIs and integrations, and the ability to work independently in a fast-paced environment. Responsibilities Design, develop, and maintain middleware applications using C# and .NET. Build and maintain integrations between Shopify and external systems. Use GraphQL to query and manipulate data from Shopify APIs. Enhance and support existing middleware services currently in production. Collaborate with cross-functional teams to define, design, and implement scalable solutions. Support and potentially transition ownership of a mobile app backend (PaaS-based). Optimize application performance, scalability, and reliability. Troubleshoot and resolve complex backend and integration issues. Write clean, maintainable, and well-documented code. Participate in code reviews and follow engineering best practices. Requirements Experience: Minimum of 4–5 years of hands-on experience with C# and .NET development. Backend Development: Strong experience building APIs, services, and middleware architectures. Shopify (Preferred): Experience working with Shopify APIs. Direct Shopify development experience is ideal. GraphQL: Solid experience using GraphQL to query and manipulate data (Shopify GraphQL Admin API experience is a plus). Cloud / PaaS: Experience working in cloud-based or PaaS environments. Integration Experience: Proven experience integrating third-party systems and APIs. Problem-Solving: Strong analytical and troubleshooting skills with the ability to resolve complex backend issues. Communication: Strong written and verbal communication skills. Ability to work effectively with client stakeholders and distributed teams. Collaboration: Experience working in an agile development environment. Remote Work This position qualifies for remote work anywhere in the United States.