Senior .Net Application Developer (Secret clearance)
Reston, VA
Experience: 14
Education: BA, BS
Category: Information Technology
Contractor Work Model: Onsite
Brand: System One
Job ID: 379174
Date Posted: 08/28/2026
Shortcut: http://jobs.systemone.com/2PrbTJ
Senior .Net Developer
Arlington, VA or Merrifield, VA - ONSITE
Secret Clearance is required to start
Must be able to obtain DEA clearance – 2-6 month process
Responsibilities:
• Works in a collaborative team environment to develop and enhance code for applications built within the Concorde framework, ensuring high-quality and efficient solutions.
• Demonstrates strong expertise in Agile development methodologies through daily activities, including sprint participation, task execution, and adherence to Agile principles.
• Participates in meetings, discussions, and demonstrations related to the development of applications and associated data across Classified, Unclassified, and Sensitive but Unclassified environments.
• Possesses the knowledge and capability to support non-Concorde legacy applications as needed, contributing to seamless integration and operational continuity.
• Possesses a foundational understanding of DevSecOps principles.
Requirements:
• Top-notch experience in Microsoft .NET languages (primarily ASP.NET, C#, and LINQ), technologies (MVC, Entity Framework, Unity), and tools (Visual Studio 2010, Team Foundation Server, ReSharper). Experience with SharePoint, NHibernate, jQuery and JavaScript, AJAX, HTML and CSS, Oracle and SQL Server databases, T4 templates, and even Classic ASP, is also desired.
• Recent 8+ years of ASP.Net C# MVC-based web development experience using Visual Studio 2017 or higher.
• 5+ years of .Net Core/Standard development experience.
• 5+ years of experience with Agile development methodologies, including participation in sprints, backlog grooming, and Agile ceremonies.
• Experience as a developer in a software environment that supported more than 10,000 users and a Relational Database Management System (RDBMS) with more than 250 tables and 1 million total rows.
• Significant recent JavaScript development experience.
• Significant development experience with Cascading System Sheets (CSS).
• Experience with relational data models and SQL.
• Experience with XML and programming libraries for XML manipulation.
• Agile project and development experience utilizing Team Foundation Server.
• Ability to quickly deliver small projects, and to frequently transition between projects and applications.
• Experience in packaging and delivering software and documentation to a production environment.
• Excellent communication skills.
• Must have an Active Secret clearance.
• Applicants selected will be subject to a government security background investigation and must meet eligibility and suitability requirements.
Education/Experience:
• Bachelor’s degree in Computer Science, Engineering, or a related field (14+ years of demonstrated experience may be substituted).
• 10+ years of general experience, including 10 years of specialized and/or hands-on experience in Agile development methodologies
System One, and its subsidiaries including Joulé 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.
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Ref: #851-Rockville-S1
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