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BlueYard Capital
BlueYard Capital

Senior Software Engineer



Software Engineering
San Francisco, CA, USA · El Segundo, CA, USA · California, USA · United States
Posted on Thursday, June 13, 2024

About Castelion

Castelion is bringing a new approach to defense development and production: one that focuses on short, iterative design cycles, rapid testing in development, and modern commercial manufacturing strategies for production at scale. We’re designing, building, and testing next generation long range strike weapons systems to give America and its Allies a definitive edge and deter future conflicts.

Senior Software Engineer

As a Senior Software Engineer you will be at the forefront of creating, developing, and testing the software that drives and simulates our flight systems. Your role involves close collaboration with fellow Castelion engineers across software and hardware domains to implement and debug software across the entire technology stack—from applications and operating systems to networking, firmware, and simulation—ensuring complete mission success. We seek intelligent, collaborative, and driven engineers who are passionate about problem-solving and eager to contribute to an extraordinary mission. If you thrive in challenging environments and are excited by the prospect of making a tangible impact, we want to hear from you.


Autonomous Systems: Design and implement reliable autonomous software systems, along with the simulations required to validate their precision and dependability.

Comprehensive Software Development: Manage the entire software development process, from initial design, prototyping, and testing, to final integration and deployment for mission-critical applications.

System Testing: Evaluate test outcomes and troubleshoot issues necessitating detailed investigations, including hands-on integration and debugging of hardware/software systems. Develop tools to facilitate testing across various environments: virtualized hardware, real hardware-in-the-loop, and vehicle-in-the-loop testing.

Collaboration: Partner with multidisciplinary engineering teams to brainstorm, design, and develop next-generation hypersonic missile capabilities, including advanced guidance algorithms and integrated seeker image processing.

Project Leadership: Lead major projects that propel Castelion’s mission forward, ensuring alignment with overall objectives and occasionally traveling to launch and customer sites for testing and operations.

Enhance Standards and Practices: Continuously improve software standards and best practices within the software team, fostering an environment of ongoing improvement and innovation.

Basic Qualifications

Educational Background: Bachelor’s degree in computer science, computer engineering, electrical engineering, math, or a related STEM field, along with over 5 years of professional software engineering experience.

Technical Proficiency: Minimum of 2 years of experience with C++, Python, or Rust, including developing in the Linux kernel including custom hardware driver development for UART and I2C peripherals.

Preferred Skills and Experience

Programming Expertise: Proven proficiency in C++, Rust, or similar systems programming languages.

System Experience: Practical experience with real-time embedded systems or distributed computing environments in Linux-based systems, including developing high-quality Linux-based C++ software for common processors and microcontrollers (e.g., PowerPC, x86, ARM).

Technical Skills: Proficiency in Linux, including Bash shell scripting, network troubleshooting, and performance analysis (strace, ftrace, etc.), with strong skills in debugging, performance optimization, and unit testing.

System Knowledge: Comprehensive understanding of computer architecture and networking protocols (TCP, UDP, etc.).

Problem-Solving: Innovative problem-solving approach using first-principles thinking, including developing prototypes to validate key design concepts and quantify technical constraints.

All employees are granted long-term stock incentives as part of their employment as Castelion. All employees receive access to comprehensive medial, vision, and dental insurance, and the company offers three weeks of paid time off per year.

Leadership Qualities

Bias to Action and Creative Problem Solving. Desire and experience questioning assumptions in ways that lead to break through ideas that are ultimately implemented. Successfully bring in applicable processes/concepts/materials from other industries to achieve efficiency gains. Ability to personally resolve minor issues in development without requiring significant support.

High Commitment, High Initiative. A successful candidate will have a genuine passion for Castelion’s mission and consistently look for ways to contribute to the company’s technical goals and prevent hardware blockers. Ability to work in a fast paced, autonomously driven, and demanding atmosphere. Strong sense of accountability and integrity.

Clear Communicator. Proactively communicates blockers. Trusted in previous roles to be voice of company with regulators, suppliers, gate keepers and customers. Capable of tactfully managing relationships with stakeholders to achieve company-desired outcomes without compromising relationships. Emails, IMs and verbal interactions are logical, drive clarity, and detailed enough to eliminate ambiguity.

ITAR Requirements:

  • To conform to U.S. Government export regulations, applicant must be a (i) U.S. citizen or national, (ii) U.S. lawful, permanent resident (aka green card holder), (iii) Refugee under 8 U.S.C. § 1157, or (iv) Asylee under 8 U.S.C. § 1158, or be eligible to obtain the required authorizations from the U.S. Department of State.

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.