Sr Principal .Net Engineer

Overview
Client is seeking a highly experienced Sr. Principal C#/.NET Engineer to help develop and modernize the Crossfire security integration platform. This is a senior, hands-on role focused on building and optimizing backend services, improving architecture, deep debugging, and accelerating delivery of high-priority features in a mission-critical environment.

Core Responsibilities

• Contribute as a principal-level engineer on core platform enhancements and ongoing maintenance

• Design, implement, and optimize high-performance C#/.NET services and integration components

• Apply event-driven, multi-threaded, and distributed system patterns

• Troubleshoot complex defects, performance issues, and reliability problems across the platform

• Drive refactoring and modernization of legacy components and architecture

• Partner with product, architecture, and QA to deliver consistent, high-quality releases

• Create technical documentation for APIs, interfaces, and deployment processes

• Provide technical leadership and mentoring as needed

Essential Qualifications, Skills, and Technologies

• 7–10 years of professional software engineering experience

• Expert proficiency with C#, .NET Framework and/or .NET Core

• Strong hands-on experience with:

  • Multi-threaded programming and concurrency

  • Event-driven or message-based architectures

  • Windows Services and system-level programming

  • Networking protocols, sockets, and real-time communications

  • Using Copilot AI and working across different models

• Proven ability to ramp quickly in large, existing codebases

• Experience building reliable, fault-tolerant backend services

• Ability to work independently with minimal ramp-up time

• Strong problem-solving and clear written communication/documentation skills

Preferred (Nice-to-Have) Skills or Experience

• Security/access control or real-time device/customer integration platforms

• SQL Server and data access (ADO.NET, Entity Framework, stored procedures)

• Diagnostic tooling, memory profiling, and performance analysis

• REST APIs, SOAP, or custom protocol integrations

• CI/CD and DevOps tooling (Azure DevOps, GitHub Actions, or similar)

• Windows memory dump analysis

Nesco Resource offers a comprehensive benefits package for our associates, which includes a MEC (Minimum Essential Coverage) plan that encompasses Medical, Vision, Dental, 401K, and EAP (Employee Assistance Program) services.

Nesco Resource provides equal employment opportunities to all employees and applicants for employment and prohibits discrimination and harassment of any type without regard to race, color, religion, age, sex, national origin, disability status, genetics, protected veteran status, sexual orientation, gender identity or expression, or any other characteristic protected by federal, state, or local laws.

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