Overview
We are seeking a highly experienced Sr. Principal C#/.NET Engineer to support the development and modernization of the Crossfire security integration platform. This is a senior technical role focused on hands-on engineering, architectural refinement, deep debugging, and accelerating delivery of high priority features.
The ideal candidate is a seasoned engineer who thrives in complex systems, understands secure real time communication patterns, and can quickly become productive in a large-scale, mission-critical codebase.
Key Responsibilities
Serve as a principal-level contributor on the Crossfire engineering team, supporting core platform enhancements and maintenance.
Design, implement, and optimize high performance C#/.NET services, frameworks, and integration components.
Work on event-driven, multi-threaded, and distributed system patterns within the Crossfire platform.
Troubleshoot and resolve complex bugs, performance bottlenecks, and reliability issues across the system.
Contribute to architectural improvements, refactoring efforts, and modernization of legacy components.
Collaborate with product owners, architects, and QA to ensure high-quality releases and technical consistency.
Develop clear technical documentation for system components, APIs, interfaces, and deployment processes.
Mentor team members and provide technical leadership where necessary.
Required Qualifications
7-10 years of professional software engineering experience.
Expert-level proficiency in C#, .NET Framework/.NET Core, and advanced debugging techniques.
Strong experience with:
Multi-threaded programming
Event-driven or message-based architectures
Windows services and system-level programming
Networking protocols, sockets, and real-time communications
Copilot AI and different models
Proven ability to quickly understand and contribute to large, existing codebases.
Experience building highly reliable, fault-tolerant backend services.
Demonstrated ability to work independently in a contract environment with minimal ramp-up time.
Excellent problem-solving skills and strong written communication/documentation ability.
Preferred Qualifications
Experience with access control/security integration platforms, or similar real-time device/customer integration systems.
Experience with:
SQL Server and data access layers (ADO.NET, EF, stored procedures)
Diagnostic tooling, memory profiling, and performance analysis
REST APIs, SOAP, or custom protocol integrations
Modern DevOps, CI/CD pipelines (Azure DevOps, GitHub Actions, etc.)
Analyzing Windows Memory dumps