> Markdown version of [/jobs/ext/628346-principal-c-net-engineer](https://www.wearedevelopers.com/jobs/ext/628346-principal-c-net-engineer). Every page supports `.md` or `Accept: text/markdown`. Links point to the HTML versions so they work for humans too. Agent guide: [/agents.md](https://www.wearedevelopers.com/agents.md). --- # Principal C#/.NET Engineer - **Company:** AllSTEM Connections - **Location:** Ontario, CA, United States - **Experience:** Expert - **Contract:** Temporary contract - **Skills:** .NET Framework, Microsoft Windows, ADO.NET, Application Programming Interfaces (APIs), Artificial Intelligence, Application Integration Architecture, Microsoft Azure, C Sharp (Programming Language), Profiling, Software Debugging, DevOps, Distributed Systems, Entity Framework, Fault Tolerance, Github, Microsoft SQL Server, Network Protocols, Performance Tuning, Software Engineering, WebRTC, Multithreading, Large Language Models, Backend, Event Driven Architecture, Information Technology, Windows Services - **Published:** June 24, 2026 - **Apply:** https://www.dice.com/job-detail/57fa9fbd-db7a-4088-aab7-8483160a63f6 ## About the Role 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 ## Description 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., Core Platform Engineering: Design, implement, and optimize high-performance C# services and frameworks for a large-scale security ecosystem. Architectural Modernization: Lead refactoring efforts and architectural improvements to modernize legacy components while maintaining system integrity. Complex Problem Solving: Troubleshoot and resolve deep-level bugs, memory bottlenecks, and reliability issues across multi-threaded and event-driven systems. Distributed Patterns: Work extensively with message-based architectures, Windows services, and real-time communication protocols (Sockets, Networking). Technical Documentation: Author clear technical documentation for complex APIs, system interfaces, and deployment processes to ensure long-term maintainability. 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