Sr. Principal C#/.NET Engineer

Sr. Principal C#/.NET Engineer (Mission-Critical Systems) We are seeking a seasoned Sr. Principal C#/.NET Engineer to lead the modernization and enhancement of a large-scale, mission-critical security integration platform. This is a high-impact technical role for a "heavy hitter" who thrives on solving deep architectural challenges and debugging complex, distributed systems. You will be responsible for accelerating the delivery of high-priority features while ensuring the platform remains highly reliable and fault-tolerant. The ideal candidate can jump into a massive, existing codebase and become productive almost immediately. Key Responsibilities Design, implement, and optimize high-performance C# services and frameworks for a large-scale security ecosystem. Lead refactoring efforts and architectural improvements to modernize legacy components while maintaining system integrity. Troubleshoot and resolve deep-level bugs, memory bottlenecks, and reliability issues across multi-threaded and event-driven systems. Work extensively with message-based architectures, Windows services, and real-time communication protocols (Sockets, Networking). Author clear technical documentation for complex APIs, system interfaces, and deployment processes to ensure long-term maintainability. Serve as a technical authority within the engineering team, providing guidance and mentorship to mid-level and senior engineers. Qualifications & Requirements Education: Bachelor's or Master's in Computer Science or a related technical field. Experience: 7–10 years of professional software engineering with a focus on backend systems. Technical Mastery Expert-level C#: Deep knowledge of the .NET ecosystem (Framework and Core). System Internals: Strong experience in multi-threaded programming and Windows system-level services. Real-Time Communications: Proficiency in networking protocols, sockets, and message-based architectures. AI Integration: Experience leveraging Copilot AI and various LLM models to accelerate development. Attributes: Proven ability to work independently in a contract environment with minimal ramp-up time and a "solution-first" mindset. Preferred Credentials Prior experience with Security Integration or Access Control platforms. Advanced diagnostic skills: Windows Memory Dump analysis, memory profiling, and performance tuning. Database expertise: SQL Server, ADO.NET, and Entity Framework. Modern DevOps fluency: Azure DevOps, GitHub Actions, and CI/CD pipeline management. Equal Opportunity Employer / Disabled / Protected Veterans #J-18808-Ljbffr AllSTEM Connections