Senior .NET Developer

This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Senior .NET Developer based in United States. This is a senior, hands-on engineering opportunity focused on building and operating a high-availability enterprise application in a secure AWS GovCloud environment. You will take technical ownership of a complex production codebase and contribute across architecture, development, deployment, troubleshooting, and continuous improvement. The platform uses a cloud-native microservices architecture processing millions of messages each month. You will work with modern .NET, PostgreSQL, RabbitMQ, AWS SQS, Docker, Kubernetes, Rancher, and AWS cloud services. The role also embraces AI-assisted software development, requiring strong engineering judgment to validate AI-generated code for security, quality, performance, and maintainability. You will collaborate closely with technical leads, operations, and engineering teams while mentoring developers and helping establish strong engineering practices. This position is well suited to an experienced developer who thrives on complex distributed systems, production ownership, and mission-critical Federal technology. Serve as a senior hands-on developer responsible for the design, development, maintenance, modernization, and continuous improvement of a large-scale production application. Take ownership of a substantial application codebase and collaborate with technical leadership to establish technical direction, engineering standards, and development best practices. Design, develop, enhance, and maintain microservices and RESTful APIs using C# and modern .NET technologies. Build and support cloud-native applications deployed in AWS, including secure Federal environments such as AWS GovCloud. Design and maintain scalable, resilient, and highly available services capable of processing millions of messages each month. Develop asynchronous and event-driven solutions using RabbitMQ, AWS SQS, and related messaging technologies. Design, develop, and optimize data access and persistence solutions using PostgreSQL and AWS RDS. Develop, deploy, troubleshoot, and maintain containerized applications using Docker and Kubernetes, including environments managed through Rancher. Support the integration and operation of machine learning capabilities within the application's microservices architecture. Use AI-assisted development tools, code-generation technologies, AI agents, and development frameworks to accelerate engineering productivity while maintaining rigorous technical standards. Review AI-generated code and validate its architecture, security, maintainability, performance, testing, and compliance with established coding standards. Conduct code reviews, mentor developers, troubleshoot complex technical issues, and contribute to engineering best practices. Maintain code quality and security through automated scanning and static analysis tools such as SonarQube. Manage source code and participate in CI/CD and DevSecOps workflows using Azure DevOps. Diagnose and resolve complex performance, scalability, reliability, messaging, database, integration, and infrastructure issues across the technology stack. Partner with operations and engineering teams to monitor production health, maintain application availability, and resolve incidents. Support production releases, deployments, troubleshooting, and incident response, including occasional after-hours support for planned releases and critical incidents. Identify and implement improvements in architecture, performance, resiliency, observability, automation, and developer productivity. Participate in Agile planning, estimation, technical design reviews, and continuous improvement initiatives. Requirements Bachelor's degree or equivalent experience in Computer Science, Engineering, Information Technology, or a related technical discipline. 8+ years of professional software development