Senior .NET Application Developer - Legacy Modernization

Clark Group; McLean (VA); Hybrid; USD 65,000 - 170,000; Full time

Benefits offered by this job

Health/dental/vision benefits

401k retirement plan

Life insurance

Commuter benefits

Tuition reimbursement

Job summary

Clark Construction Group in McLean, VA seeks a Senior Application Developer to own and modernize enterprise Microsoft stack apps. You’ll maintain and enhance critical legacy systems, analyze complex logic, and design scalable improvements while collaborating with IT leadership and vendors.

You will implement RESTful APIs, optimize T-SQL and database objects, and help drive modern development practices, including source control and CI/CD, in an onsite setting.

Qualifications

• 6+ years of experience developing and supporting applications in the Microsoft ecosystem.
• Strong experience with .NET Framework applications (WebForms, MVC, WCF, or similar).
• Experience with SQL Server and IIS hosting.
• Experience with existing / legacy (brownfield) systems.

Responsibilities

• Serve as the primary technical owner for internally developed web applications built on the Microsoft stack (.NET Framework, SQL Server, IIS).
• Maintain, troubleshoot, and enhance legacy applications to ensure stability and performance for business-critical operations.
• Analyze and reverse-engineer existing systems to understand business logic, database structures, and integrations where documentation is limited.
• Design and implement improvements to application architecture, code structure, and database design to support long-term maintainability.
• Write, refactor, and optimize complex T-SQL queries, stored procedures, and database objects in Microsoft SQL Server.
• Support and manage IIS-hosted applications, including deployment, configuration, and security updates.
• Develop new functionality using C#, .NET, JavaScript, and related technologies.
• Build RESTful APIs or service layers to enable integration between legacy systems and newer applications.
• Contribute to technical decisions related to system modernization, including upgrades, refactoring, cloud migration, or evaluation of COTS solutions.
• Help establish modern development practices such as source control, automated builds, testing, and deployment processes.
• Collaborate with business stakeholders to understand existing workflows and translate them into technical solutions.
• Document system behavior, architecture, and dependencies to improve long-term supportability.
• Provide technical leadership for the platform while remaining hands-on in development and support.

Skills

C#

VB.NET

SQL Server

HTML

CSS

JavaScript

Education

Bachelor's degree in Computer Science or related field

Tools

IIS

Visual Studio

Job description

Clark Construction Group in McLean, VA seeks a Senior Application Developer to own and modernize enterprise Microsoft stack apps. You’ll maintain and enhance critical legacy systems, analyze complex logic, and design scalable improvements while collaborating with IT leadership and vendors.

You will implement RESTful APIs, optimize T-SQL and database objects, and help drive modern development practices, including source control and CI/CD, in an onsite setting.