Leidos is seeking a Principal Software Engineer (C#) to work for the Security Enterprise Solutions (SES) business unit in Vista, CA. The SES business unit at Leidos designs and manufactures highly complex security equipment for use at border crossings, airports, seaports, and other transportation mechanisms. Our products include radiation detectors and spectrometers, X-ray and gamma ray scanners for cars, trucks and trains, and CT explosives detection equipment for airline passenger baggage. The ultimate goal for this position will be to update existing design as well as introduce new products to our already extensive line of security detection products. The products being developed through this effort are truly novel, and will make travel and trade safer, healthier, and more efficient on a global level. We are seeking candidates local to Vista CA that have the ability to work a hybrid schedule (3 days remote, 2 days onsite). The Principal Software Engineer (C#) will serve as a senior member of the technical team, providing technical leadership and expertise while fostering collaboration and team consensus. This individual will play a key role in driving innovation, enhancing security compliance, and mentoring other engineers. As part of a cross-functional team, the Principal Software Engineer will develop and maintain cargo inspection detection systems for the Ports and Borders group at Leidos. This role requires advanced technical expertise, a commitment to best practices, and a focus on delivering high-quality, secure software solutions.