Sr. Principal C#/.NET Engineer

Codeworks, an LRS company, is seeking a Sr. Principal C#/.NET Engineer for a Contract opportunity. This role offers the chance to apply your engineering expertise in support of meaningful modernization work for one of our client partners. Our client is looking for a Sr. Principal C#/.NET Engineer to support the development and modernization of the Crossfire security integration platform. This senior, hands‑on role focuses on engineering excellence, architectural refinement, deep debugging, and accelerating delivery of high‑priority features. The position involves working in complex, large‑scale systems and secure, real‑time communication environments. Key Responsibilities Serve as a principal 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 with event‑driven, multi‑threaded, and distributed system patterns within the Crossfire platform. Troubleshoot and resolve complex defects, performance bottlenecks, and reliability issues across the system. Contribute to architectural improvements, refactoring, and modernization of legacy components. Collaborate with product owners, architects, and QA to deliver high‑quality releases and maintain technical consistency. Produce clear technical documentation for system components, APIs, interfaces, and deployment processes. Provide mentoring and technical leadership to team members, as needed. Required Qualifications 7+ of professional software engineering experience or equivalent depth of experience. Advanced proficiency in C#, .NET Framework/.NET Core, and modern debugging techniques. Hands‑on experience with: Multi‑threaded programming Event‑driven or message‑based architectures Windows services and system‑level programming Networking protocols, sockets, and real‑time communications AI coding assistants (e.g., GitHub Copilot) and related models/tools Proven ability to understand and contribute to large, existing codebases. Experience building highly reliable, fault‑tolerant backend services. Ability to operate autonomously in a contract role and become productive quickly. Strong problem‑solving skills and clear written communication/documentation. The base range for this contract position is $75.00 - $85.00 per hour, depending on experience. The range displayed reflects the minimum and maximum target for new hires of this position across all U.S. locations. Individual pay is determined by work location and additional job-related factors. Codeworks, an LRS company, is an equal opportunity employer. Applicants for employment will receive consideration without unlawful discrimination based on race, color, religion, creed, national origin, sex, age, disability, marital status, gender identity, domestic partner status, sexual orientation, genetic information, citizenship, status or protected veteran status. In some cases, Codeworks, an LRS company, uses generative artificial intelligence ("AI") in support of our hiring processes. Codeworks takes steps to ensure the use of AI does not result in discrimination based on protected class(es). AI may be used in the hiring process solely in support of the assessment of candidate qualifications. All decisions in the hiring process are made by LRS employees. If AI will be used in the hiring process for the position for which you are applying, you will be notified and will have the opportunity to opt out. Please contact AI.Questions@lrs.com with any questions.