Senior Software Engineer

NextGen Federal Systems, LLC is seeking a Software Engineer with experience in Systems Tool Kit (STK) to support the development and integration of mission analysis and modeling applications. These applications enable multi-domain analysis—including air, space, ground, and maritime systems—by leveraging physics-based modeling and simulation to assess system performance, coverage, communications, and operational effectiveness.

Responsibilities include software development, configuration, and execution; result interpretation; documentation; and modification and maintenance of tools and code. The selected candidate must be quick to learn, adaptable, and agile, interfacing directly with end-customers and customer leadership. The software engineer will provide a full range of systems and software engineering to support critical mission analyses.

• Develop, customize, and maintain STK-based applications to support mission planning, analysis, and visualization
• Integrate STK (Engine, Components, or Desktop) with external tools, models, and data sources to enable end-to-end mission workflows
• Implement backend services using Python and support frontend interfaces as needed
• Analyze and interpret simulation results, providing actionable insights to engineering teams and stakeholders
• Support traceability between mission analysis outputs and system models, ensuring consistency across the digital engineering environment
• Support deployment and execution of applications in modern environments (e.g., containerized or cloud-based)
• Contribute to documentation, user guides, and technical deliverables
• Troubleshoot and enhance existing tools to improve performance, usability, and scalability

• BS or equivalent in Computer Science, Engineering, Mathematics, or equivalent technical degree
• 5+ years’ prior work experience in the aerospace or defense industry, with demonstrated software development experience
• Experience customizing or automating STK-based tools or applications highly desired (including STK, STK Engine, STK Components, and/or Cesium)
• Experience integrating tools via APIs (REST or similar)
• Proficiency in Python and experience with backend frameworks such as Flask is required
• Strong expertise in React JS for building modern and responsive user interfaces is highly desirable
• Knowledge of version control systems, preferably Git is highly desirable
• Proven experience as a Full Stack Developer or similar role is highly desirable
• Capable of self-management and responsibly executing multiple tasks in accordance with priorities and deadlines
• Active Top Secret (TS) clearance required (SCI eligibility preferred)

• Experience with STK Engine, STK Components, or Cesium
• Experience linking STK analyses to MBSE environments (e.g., parameter passing, trade studies, digital thread integration)
• Familiarity with digital engineering ecosystems, mission thread development, or model orchestration tools
• Experience with Docker, cloud environments, or DevSecOps practices
• Frontend development experience (e.g., React)