Senior Application Developer

Green Key is seeking a Senior Application Developer to join an established organization in Northern Virginia. This is a highly hands-on opportunity for an experienced developer who enjoys working with legacy applications, troubleshooting complex systems, and identifying opportunities to modernize and improve existing technology.

The ideal candidate will be someone who can step into an established application environment, learn how the system works from the ground up, identify areas for improvement, and make thoughtful recommendations around enhancements, modernization, or future technology solutions.

This position will have significant ownership of a business-critical internal application and will work closely with leadership and business stakeholders.

What You’ll Do

• Take ownership of an internally developed application and its ongoing support and enhancement.
• Troubleshoot complex application issues and identify opportunities for improvement.
• Analyze existing code, databases, integrations, and business processes.
• Work within legacy systems where documentation may be limited.
• Develop a strong understanding of how existing applications function and interact.
• Recommend improvements to application architecture, functionality, performance, and maintainability.
• Develop and enhance applications using C#, .NET, SQL Server, JavaScript, and related technologies.
• Write and optimize SQL queries, stored procedures, and database objects.
• Support applications running in IIS environments.
• Develop APIs and integrations between existing and newer technologies.
• Evaluate opportunities to modernize applications or implement alternative technology solutions.
• Research new applications and technologies and provide recommendations to leadership.
• Collaborate with business stakeholders to understand requirements and translate them into technical solutions.
• Improve technical documentation and establish more sustainable development practices.
• Remain hands-on while serving as a key technical resource for the application environment.

• Bachelor’s degree in Computer Science, Software Engineering, Information Systems, or a related field.
• 6+ years of application development and support experience.
• Strong experience with C#, VB.NET, and Microsoft SQL Server.
• Experience with .NET Framework applications.
• Experience supporting legacy or “brownfield” applications.
• Strong SQL development and troubleshooting experience.
• Experience with IIS-hosted applications.
• Working knowledge of HTML, CSS, and JavaScript.
• Strong analytical and problem-solving skills.
• Ability to independently troubleshoot and understand complex applications.
• Strong communication skills and a high level of professionalism.
• Ability to communicate effectively with both technical and non-technical stakeholders.

Nice to Have

• Experience modernizing legacy .NET applications.
• Experience with newer versions of .NET.
• Azure or AWS experience.
• API and systems integration experience.
• Git, Azure DevOps, or CI/CD experience.
• Experience evaluating new software or commercial solutions.
• Experience with PowerApps, Mendix, or other low-code platforms.
• Experience improving legacy database architecture.