The Senior Application Developer is responsible for ensuring the stability, support, and continuous modernization of critical enterprise applications that underpin core business operations. This role will serve as the primary technical owner of a mission-critical legacy environment built on the Microsoft stack, which includes the .NET Framework, SQL Server, and IIS. The developer will ensure reliable daily operations while helping to transition the system to modern architecture and development practices.

This position requires a hands-on developer comfortable working in complex, undocumented systems who can balance immediate support needs with long-term improvements. The role will collaborate closely with IT leadership, business stakeholders, and external vendors to maintain the current platform while contributing to decisions regarding upgrades, refactoring, or potential replacement with modern or commercial solutions.

This is an onsite role based in our McLean, VA o...