Senior Software Engineer (.NET​/C#​/Azure

OnTrac is seeking a Senior Software Engineer (.NET / C# / Azure) to join a contractor program supporting a large wholesale digital-marketplace customer. The customer is rebuilding its digital auction platform and decoupling it from a legacy auction management system, standing up a new, independent, modern auction backend purpose-built for a digital-first marketplace. Phase 1 delivers the core platform: inventory management, financial transactions, and customer management.

The initiative is broad in scope and spans four or more teams. This role is ideal for a hands‑on senior engineer who writes production C# on .NET Core, is comfortable on Azure and Azure Dev Ops, and can collaborate across teams to turn business requirements into maintainable, scalable software.

• Expected start: ASAP
• Location:
  
  United States, fully remote

• Implement core features for the new platform, which could include inventory management, financial transactions, and customer management
• Collaborate closely with team members, other teams, and product managers to translate business requirements into technical solutions
• Develop high-quality, maintainable, and efficient C# code within an agile development environment
• Design and implement efficient data models and database interactions
• Integrate the new system with existing platforms and third-party systems
• Conduct code reviews and provide constructive feedback to peers
• Troubleshoot and debug issues, ensuring optimal performance and reliability
• Contribute to technical documentation and best practices

• Bachelor's degree in Computer Science, Software Engineering, or a related field
• 7+ years of experience in C# development, with a strong understanding of object‑oriented programming principles
• Extensive experience with .NET Core and C#
• Familiarity with front-end development using modern frameworks, specifically React
• Experience with the Microsoft Azure cloud platform, including core services and infrastructure
• Experience creating and optimizing CI/CD pipelines, specifically within Azure Dev Ops
• Understanding of software architecture principles and best practices, with proficiency in applying design patterns to solve technical challenges
• Proficiency in designing and developing RESTful APIs
• Solid understanding of database systems and storage (e.g., SQL Server, PostgreSQL, No
  
  SQL) and ORM frameworks (e.g., Entity Framework)
• Demonstrated ability to write clean, testable, and efficient code
• Strong problem-solving skills and attention to detail
• Excellent communication and collaboration skills
• Experience with agentic workflows
• Comfortable working with AI and AI‑assisted development tools

• Contemporary JavaScript / Type Script (ES2015+), React Hooks, Next.js, Nx
• Experience with a message queue such as Kafka or RabbitMQ
• Experience writing GraphQL‑interfaced services
• Experience working with authentication and authorization