Ground Software Engineer Torrance, CA Mechanical Engineering

Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus, ownership, and excellence are decisive advantages - and we're building a world-class team to turn bold ideas into real capability.

This is a rare opportunity to join at an early stage, where you'll have significant ownership, collaborate with exceptional teammates, and make a direct, measurable impact on our mission and the future of the company - regardless of your function.

Ground Software Engineer on the Flight Software team is responsible for building the software systems that connect engineers to flight hardware throughout development, integration, testing, and flight operations. In this role, you will develop vehicle command and control systems, telemetry infrastructure, test automation tools, and mission-critical software that enables rapid iteration of Castelion's next-generation strike systems.

This position offers the opportunity to work at the intersection of software, hardware, and flight testing, making a direct contribution to accelerating vehicle development and increasing flight-test velocity.

• 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

• 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

• 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

Castelion offers a generous benefits package. Please refer to the bottom of our Careers page for more details.

Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee for this job. Duties, responsibilities and activities may change at any time with or without notice.

This position may require access to classified information or restricted U.S. Government sites, systems, or information, as determined by the Company and/or applicable U.S. Government requirements. If the position is so designated, your employment in the role may be contingent upon your ability to obtain and maintain the required U.S. Government security clearance or other government authorization, and to satisfy any citizenship or other eligibility requirements imposed by applicable law, regulation, executive order, or government contract requirements.

You will be notified if and when such requirements apply.

Castelion is an Equal Opportunity Employer. We are committed to providing equal employment opportunities to all applicants and employees without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, age, disability, genetic information, protected veteran status, or any other characteristic protected by applicable federal, state, or local law.

Castelion is committed to providing reasonable accommodations to qualified individuals with disabilities throughout the application and hiring process. If you require a reasonable…