Senior Applied AI Engineer

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, 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.

Senior Applied AI Engineer

Castelion is seeking a Senior Applied AI Engineer to design, build, and integrate AI tools and workflows that address business needs across the organization, including engineering, supply chain, and flight test. You will bridge business needs and technical execution-defining requirements, designing solutions, and delivering production-ready AI systems that solve real problems.

This role will work cross-functionally across the company and report directly to the Head of Flight Software.

Responsibilities

• Collaborate with teams across the company to define Castelion’s AI tooling and integration roadmap
• Architect and implement scalable, production-ready AI integrations for a wide range of use cases across the organization
• Integrate AI tools with existing enterprise systems and data sources
• Partner with IT, programs and cybersecurity teams to ensure compliance with customer and internal security policies
• Establish and maintain organization-wide AI development standards, including model selection criteria, prompt engineering best practices, and governance frameworks
• Assess emerging AI technologies to drive strategic internal adoption

Basic Qualifications

• 7+ years of software development experience with proficiency Python and one static language (e.g. C, C++, C#, Java)
• 2+ years of Applied AI experience owning an AI agent, LLM-powered workflow, or automation end-to-end from prototype through production
• Understanding of prompt engineering, fine-tuning, and model evaluation
• Hands-on experience with RAG architecture, vector databases, and embedding models
• Strong experience collaborating with diverse stakeholders to gather requirements and develop tools that effectively address their needs
• Bachelor’s degree in computer science (preferred) or another STEM field or equivalent work experience

Preferred Skills and Experience

• 10+ years of software development experience
• Experience deploying self-hosted AI platforms on cloud infrastructure (Azure/AWS/GCP)
• Experience leveraging Model Context Protocol (MCP) to integrate enterprise data sources with AI tools and applications
• Knowledge of automated containerized deployment
• Comfortable working in a fast-paced, high growth environment with rapidly evolving business needs
• Experience building and leading small teams

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

Other Duties

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.

Additional Eligibility Requirements

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.

Affirmative Action/EEO Statement

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 accommodation to complete an application, participate in the interview process, or otherwise participate in the hiring process, please contact View email address on aiapply.co. Requests for accommodation will be considered on an individual basis and handled in accordance with applicable law.

Castelion is committed to fostering a workplace where employment decisions are based on qualifications, business needs, and the ability to perform the essential functions of the role, with or without reasonable accommodation.

EAR/ITAR Requirements

This position requires access to export-controlled information, and as such, employment (or hiring of a contractor) is contingent upon the candidate’s ability to access all applicable export-controlled information without additional export licensing being required by the Bureau of Industry and Security and/or the Directorate of Defense Trade Controls.