Why Castelion, Why Now
Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus and technical excellence are decisive advantages - and we are building a team that can deliver real capability, not just concepts.
This is a rare opportunity to join at an early stage, where your work will directly shape critical systems, influence major technical decisions, and have immediate, real-world impact.
Ground Software Engineer
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.
Responsibilities
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 Basic Qualifications
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 Preferred Skills and Experience
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 And Perks
All full-time employees are granted meaningful long-term equity, sharing in the company's significant growth trajectory. We offer four (4) weeks of paid time off, ten (10) company-paid holidays, and comprehensive health benefits - including 100% employee-covered medical and strong dependent coverage, along with dental and vision plans. We also provide paid parental leave to support growing families, a $100 monthly fitness stipend to promote health and performance, and onsite EV charging for convenience. In addition, employees enjoy perks like catered meals, company-covered food during high-demand periods, and a fully stocked kitchen to stay fueled throughout the day.
While this position does not currently require a U.S government-issued security clearance, it may in the near future. Therefore, 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.
Affirmative Action/EEO Statement
Employment with Castelion is governed on the basis of competence and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status.
