Ground Software Engineer

Castelion is rapidly developing advanced defense systems and is looking for a Ground Software Engineer to join their Flight Software team. This role involves building software systems that connect engineers to flight hardware, developing vehicle command and control systems, and contributing to flight testing operations.

What you'll do:

• Design, develop, and maintain software systems for vehicle command, control, telemetry, and test operations
• Build and support ground software infrastructure used for hardware-in-the-loop (HIL), integration, and flight testing
• Develop backend services, automation tools, telemetry pipelines, and operator-facing applications using Python and modern software frameworks
• Integrate software with avionics, flight computers, test equipment, and communication systems to enable end-to-end vehicle testing
• Support flight campaigns, system debugging, and root-cause investigations across software and hardware interfaces

What they're looking for:

• Bachelor's degree in Computer Science, Electrical Engineering, Aerospace Engineering, or a related technical field
• 1+ years of professional software engineering experience with strong proficiency in Python
• Experience developing software on Linux systems and working with networking protocols such as TCP/IP and UDP
• Experience building backend services, distributed systems, automation frameworks, or hardware-integrated software systems
• The ability to obtain and maintain a U.S. government–issued security clearance is required
• U.S. citizenship is required, as only U.S. citizens are eligible for a security clearance
• Experience supporting aerospace, defense, robotics, autonomous systems, or other mission-critical hardware programs
• Experience with telemetry systems, real-time data processing, time-series databases, or data visualization platforms
• Experience with Docker, Kubernetes, CI/CD pipelines, and modern software deployment practices
• Experience supporting hardware-in-the-loop (HIL) testing, system integration, or flight test operations
• Experience developing operator interfaces, mission control systems, or engineering tools using React, Vue, or similar frameworks

Benefits:

• Meaningful long-term equity, sharing in the company's significant growth trajectory
• Four (4) weeks of paid time off
• Ten (10) company-paid holidays
• Comprehensive health benefits - including 100% employee-covered medical and strong dependent coverage, along with dental and vision plans
• Paid parental leave to support growing families
• $100 monthly fitness stipend to promote health and performance
• Onsite EV charging for convenience
• Perks like catered meals, company-covered food during high-demand periods, and a fully stocked kitchen to stay fueled throughout the day