Sr. C# Developer
Washington, DC
Experience: 12
Education: BA
Category: Information Technology
Contractor Work Model: Onsite
Brand: System One
Compensation Range: 73.50 - 90.00 Per Hour
Job ID: 345972
Date Posted: 02/06/2026
Shortcut: http://jobs.systemone.com/MpIQ77
Job Title: Sr. Software Developer (C#/ .NET)
Location: Washington, DC (5 days a week in the office)
Type: W2 Contract Only
Compensation: $73.50 - $90.00 W2 hourly
Contractor Work Model: 100% On-site
Security Clearance: Per government contract, must be a U.S. citizen and able to obtain a Public Trust clearance. (DOJ Public Trust preferred).
System One is hiring a Senior C# Software Developer on the ESA V program. ESA V is an IT applications and infrastructure services program supporting several customers within the Department of Justice (DOJ). The program provides a range of IT services, including software application support, enterprise infrastructure support, service desk, ITSM, deskside support, workstation engineering and maintenance, telecommunications and mobility engineering services, managed print services, Active Directory services, and video conferencing. The ideal candidate will be personable and articulate and will focus on making sure that the customer’s needs are met quickly and effectively. The successful candidate will be a self-starter who can work with limited supervision. Excellent communication skills are required to effectively interface with customers to understand requirements and mission needs and then be able to translate them into actions.
Currently, this position is required to be onsite full time in Washington, DC metro area at one of the primary customer (CRM) locations.
Primary Responsibilities.
- Work at the direction of the program manager to support the full lifecycle development of custom applications, primarily using the C# and the .NET ecosystem.
- Design, develop, and test high quality of C# and .NET applications.
- Collaborate with program manager, business analysts, and other engineers to translate business requirements into technical solutions
- Lead or contribute to architectural decisions and technical designs
- Troubleshoot, debug, and optimize application performance
- Monitor and provide operational support to applications.
- Basic Qualifications. Typically requires BS degree and 12 – 15 years of prior relevant experience or Masters with 10 – 13 years of prior relevant experience. May possess a Doctorate in technical domain.
- U.S. Citizen
- Ability to obtain and maintain a public trust security clearance
- Strong proficiency in C# and .NET/.NET Core framework
- Experience building and maintaining backend services and APIs
- Experience establishing goals and meeting project plan objectives
- Solid understanding of object-oriented design principles and patterns
- Experience with relational databases (Oracle)
- Must be able to write and maintain system documentation on work products
- Experience with GitLab for source control
- Excellent communication and teamwork skills
- Agile development experience
- Customer interface experience
- Experience with modern web frameworks (ASP.NET Core, REST APIs)
- Knowledge and experience developing using Model, View, and Controller (MVC) architecture
- Knowledge of CI/CD pipelines and automated testing
- Familiarity with frontend technologies (React, Angular, etc)
- Experience troubleshooting operational issues
- Government contracting experience, particularly with the DOJ
- Current DOJ Clearance
System One, and its subsidiaries including Joulé, ALTA IT Services, and Mountain Ltd., are leaders in delivering outsourced services and workforce solutions across North America. We help clients get work done more efficiently and economically, without compromising quality. System One not only serves as a valued partner for our clients, but we offer eligible employees health and welfare benefits coverage options including medical, dental, vision, spending accounts, life insurance, voluntary plans, as well as participation in a 401(k) plan.
System One is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender identity, age, national origin, disability, family care or medical leave status, genetic information, veteran status, marital status, or any other characteristic protected by applicable federal, state, or local law.
#M-
#LI-
#DI-
Ref: #851-Rockville-S1
-
I&C Engineer (Remote)
Groton, NE
Job Title: I&C Engineer VI Location: Remote Type: Contract Compensation: DOE Contractor Work Model: Remote Number of positions: 1 Duration: 12 months Non Exempt Work Schedule: 8:00 am - 5:00 pm Category: Engineering Technology System One is hiring an e...
Date Posted: 12/10/2025 Recommended
-
I&C Manufacturing Engineer
Corvillas, OR
Job Title: I&C Manufacturing Engineer Location: Corvillas, OR Type: Direct Hire Compensation: $111,000 - $134,000 annually Work Model: Remote with 10-25% travel required System one is hiring a direct full-time I&C Manufacturing Engineer who will be res...
Date Posted: 01/30/2026 Recommended
-
Nuclear Project Manager (I&C)
Houston, Texas
System One is seeking Project Manager for a long-term contract role who will lead a diverse team with various departments to advance our client’s Small Modular Reactor design, fabrication and deployment. This position focuses on development scope for P...
Date Posted: 01/30/2026 Recommended
-
Construction Manager-Port Washington
Port Washington, Wisconsin
The data center boom is real—and we’re building the future. Get in on the action and apply today! Job Title: Data Center Construction Manager Location: Port Washington, WI Type: Full-Time Project (12-24 months) About the Role We’re seeking a seasoned D...
Date Posted: 11/18/2025 Recommended
-
Systems Engineer - Linux / Windows
Merrifield, Virginia
Senior System Engineer, Linux/Windows Direct Hire First 6 months on-site, Fairfax, VA – then hybrid 2 days a week on-site thereafter Salary: $120,000 to $125,000 annually, plus benefits Federal End-Client: US Citizenship required, eligible for Public T...
Date Posted: 01/30/2026 Recommended
-
I&C Technician
Oak Ridge, Tennessee
Job Title: Electronics Lab Technician Location: Oak Ridge, Tennessee Type: Direct Hire Contractor Work Model: Onsite System One is seeking an Electronics Lab Technician for a direct hire opportunity based in Oak Ridge, TN. In this pivotal role, you wil...
Date Posted: 11/10/2025 Recommended
-
Nuclear Digital I&C IV&V Engineer
Corvallis, Oregon
Job Title: Nuclear Digital I&C IV&V Engineer Location: Corvallis, Oregon Type: Contract Contractor Work Model: Remote Job Description: Are you an expert in Independent Verification and Validation (IV&V) with a passion for ensuring the safety and reliab...
Date Posted: 02/02/2026 Recommended
-
I&C Design Engineer
Bellevue, WA
Job Title: Design Engineer Type: Contract Compensation: $52 - $85 hourly Contractor Work Model: Remote Overview: We are seeking a talented and experienced Design Engineer specializing in Instrumentation and Control (I&C) for a contract opportunity with...
Date Posted: 01/05/2026 Recommended
-
Electrical I&C Engineering Supervisor, Nuclear
Naperville, Illinois
Job Title: Electrical I&C Engineering Supervisor, Nuclear Location: Naperville, Illinois or Atlanta, GA Type: Direct Hire Contractor Work Model: Hyrbrid or Remote We are seeking an experienced Electrical I&C Engineering Supervisor to join a dynamic tea...
Date Posted: 12/15/2025 Recommended
-
I&C Design Engineer
Bellevue, WA
Job Title: I&C Design Engineer Type: 12-month Contract Compensation: $84 - $135 hourly Contractor Work Model: Remote Position Overview: We are seeking a skilled I&C Design Engineer for a long-term contract opportunity, with a remote work model. This pi...
Date Posted: 01/12/2026 Recommended
-
Thermal Analysis Engineer
Bellevue, WA
Job Title: Thermal Analysis Engineer Location: Bellevue, WA Type: Contract (yearlong) typically extends on a yearly basis Compensation: $52 - $85 hourly Contractor Work Model: Fully Remote Paid Holidays | PTO System One is seeking a highly motivated Th...
Date Posted: 01/30/2026 Recommended
-
Senior Safety Methods Engineer
Bellevue, WA
Job Title: Senior Safety Methods Engineer Location: Bellevue, WA Type: Contract (yearlong) typically extends on a yearly basis Compensation: $69 - $115 hourly Contractor Work Model: Fully Remote Paid holidays and PTO System One is seeking a Senior Safe...
Date Posted: 01/27/2026 Recommended
-
Google Cloud Platform (GCP) Engineer
Washington, DC
Google Cloud Platform (GCP) Engineer 100% ONSITE- SE Washington, DC 20590 Target Start Date 3/9/2026 Per Federal Contract U.S. Citizenship or valid green card Required Must be able to pass Federal Background investigation for Public Trust Clearance $57...
Date Posted: 01/26/2026 Recommended
-
Technical Program Manager (Top Secret)
Arlington, Virginia
Technical Program Manager Top Secret Clearance required to start Hybrid - 1 day a week onsite in Sterling and 1 day a week onsite in DC Direct Hire System One is seeking a Technical Program Manager to support our Department of State client within the B...
Date Posted: 01/27/2026 Recommended
-
Sr. Sharepoint Solution Developer
Columbus, Ohio
System One has a contract opportunity with a client in the Columbus, OH Area. This role is located onsite at their headquarter offices. The right candidate will be well versed in .NET & Sharepoint 2019. W2 Contract, not open to c2c or sponsorships. Sen...
Date Posted: 02/03/2026 Recommended
-
Platform Engineer - Cloud - Azure
Washington, DC
Senior Platform Engineer – Azure (Federal Program) Location: Onsite – Washington, DC Level: Senior / Lead Individual Contributor Clearance: Ability to obtain public trust(preferred) Why This Role Matters We’re supporting a high-impact federal program w...
Date Posted: 01/27/2026 Recommended
-
Senior Database Engineer
Washington, DC
Job Title: Senior Database Engineer Location: SE Washington, DC 20590 (onsite) Type: Contract Compensation: $45.00-$52.89/HR on W2 Security Clearance: Candidate must be a U.S. citizen or green card holder who has resided in the U.S. for at least 3 year...
Date Posted: 01/27/2026 Recommended
-
Tier 2 Deskside/System Technician
Rockville, MD
Job Title: Tier 2 Deskside/System Technician Location: Rockville, MD or Bluemont, VA -some travel will be required between HQ (Rockville, MD) and Mount Weather (Bluemont, VA) locations (whenever needed) Type: Contract Compensation: $34.00 hourly Contra...
Date Posted: 01/30/2026 Recommended
-
Project EHS Manager
Oakland, California
Job Title: Project EHS Manager Location: Oakland, California Type: Direct Hire Compensation: $109000 - $170000 annually Contractor Work Model: Onsite Hours: Add the job’s scheduled days and times (delete if not needed) Security Clearance: List security...
Date Posted: 12/02/2025 Recommended
-
Benefits Analyst
Nashville, TN
Job Title: Benefits Analyst Location: Nashville, TN Type: Contract Compensation: Contractor Work Model: Hybrid Hours: Add the job’s scheduled days and times (delete if not needed) Security Clearance: List security clearance requirements (delete if not ...
Date Posted: 01/27/2026 Recommended
-
Reactor Core and Component System Design Engineer
Bellevue, WA
Job Title: Reactor Core and Component System Design Engineer Location: Bellevue, WA Type: Long-term Contract Compensation: $69 - $115 hourly Contractor Work Model: Remote Position Overview: We are seeking a highly skilled and motivated Reactor Core and...
Date Posted: 12/15/2025 Recommended
-
Staff Engineering Technician
Denver, Colorado
Staff Engineering Technician Denver, CO 80237 System One is seeking a Staff Engineering Technician in Denver, CO to perform advanced functions requiring technical knowledge and use of electronic applications, standards, and document control processes/p...
Date Posted: 01/29/2026 Recommended
-
Staff Engineering Technician
Houston, Texas
Staff Engineering Technician Houston, TX 77079 System One is seeking a Staff Engineering Technician in Houston, TX to perform advanced functions requiring technical knowledge and use of electronic applications, standards, and document control processes...
Date Posted: 01/29/2026 Recommended
-
Staff Engineering Technician
Jacksonville, Florida
Staff Engineering Technician Jacksonville, FL 32258 System One is seeking a Staff Engineering Technician in Jacksonville, FL to perform advanced functions requiring technical knowledge and use of electronic applications, standards, and document control...
Date Posted: 01/29/2026 Recommended
-
Staff Engineering Technician
Orlando, Florida
Staff Engineering Technician Orlando, FL 32801 System One is seeking a Staff Engineering Technician in Orlando, FL to perform advanced functions requiring technical knowledge and use of electronic applications, standards, and document control processes...
Date Posted: 01/29/2026 Recommended
-
Electrical Engineer
Birmingham, Alabama
Job Title: Electrical Engineer Location: Birmingham, Alabama Type: 12 month Contract Compensation: $50.00 hourly Contractor Work Model: Onsite System One is currently seeking an Electrical Engineer on a 12 month contract position located in Birmingham,...
Date Posted: 01/29/2026 Recommended
-
Staff Engineering Technician
Overland Park, KS
Staff Engineering Technician Overland Park, KS System One is seeking a Staff Engineering Technician to perform advanced functions requiring technical knowledge and use of electronic applications, standards, and document control processes/procedures in ...
Date Posted: 01/28/2026 Recommended
-
Weld Engineer
Bellevue, WA
Job Title: Weld Engineer Location: Bellevue, WA (local candidates only) Type: Contract (yearlong) typically extends on a yearly basis Compensation: $52 - $85 hourly Contractor Work Model: Onsite Paid Holidays | PTO System One is seeking a highly motiva...
Date Posted: 01/16/2026 Recommended
-
Director of IT Mergers and Acquisitions ( IT M&A Director)
Pittsburgh, Pennsylvania
Job Title: IT Director - M&A Location: Pittsburgh, Pennsylvania Type: Direct Hire Contractor Work Model: Hybrid Hours: Add the job’s scheduled days and times (delete if not needed) Security Clearance: List security clearance requirements (delete if not...
Date Posted: 02/05/2026 Recommended
-
Full Stack Tech Lead (Python, .Net, and C#)
Ashburn, VA
If interested reach out directly to kimberly.spicer@systemone.com or call/text 301-252-8762 Full Stack Tech Lead (Python, .Net, and C#) Ashburn, VA Customs Border Protection.- CBP-ITI Project. Integrated Traveler Initiative. Hybrid-Remote - Requires 2 ...
Date Posted: 01/28/2026 Recommended