Cloud Compute Engineer

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.

Castelion is seeking a Cloud Compute Engineer to build and own the Seeker Team's scalable cloud compute platform for data processing, simulation, calibration, and machine learning. You will move compute-intensive workflows from individual laptops and one-off scripts into a shared, automated, and reliable platform that supports multiple engineering teams.

Working across data processing, ML training, and test infrastructure, you will build distributed compute systems, optimize Python workloads, and integrate simulation and regression testing into CI/CD pipelines. This is a hands-on role with significant impact on engineering productivity, data-processing speed, and the scalability of Castelion's seeker development.

• Build a shared compute platform: Develop and operate distributed compute infrastructure supporting batch processing, custom jobs, simulation, calibration, preprocessing, and ML training.
• Automate data processing: Build event-driven workflows that automatically process newly ingested data, including flight-test and chamber calibration data.
• Scale compute-intensive workloads: Enable scalable ML training, Foxglove RDL preprocessing, data preparation, replay, and other user-submitted jobs.
• Integrate compute with CI/CD: Enable simulation and regression tests to run automatically in CI/CD pipelines, expanding test coverage beyond standard runner limitations.
• Optimize performance and cost: Profile and improve Python workloads, data flows, memory usage, concurrency, and resource utilization—not just the underlying infrastructure.
• Improve the developer experience: Provide simple interfaces, APIs, or SDKs for engineers to submit, monitor, debug, and rerun jobs without managing infrastructure manually.
• Ensure reliability and observability: Implement logging, metrics, alerting, job traceability, and cost monitoring to make failures easy to diagnose and recover from.
• Enable reproducible workflows: Track code versions, inputs, configurations, and outputs so compute jobs can be reliably reproduced and audited.
• Support large-scale data movement: Design efficient approaches to storage, data transfer, caching, partitioning, and preprocessing.
• Drive adoption across teams: Work directly with engineers to understand their workflows and establish consistent compute patterns across unclassified and classified networks.

• Experience building and operating distributed compute platforms used by multiple engineering teams.
• Strong Python skills, including profiling, concurrency, memory management, and performance optimization.
• Production experience with Ray and Kubernetes.
• Experience designing batch-processing, event-driven, and user-submitted job systems.
• Experience with Azure compute, storage, networking, identity, and monitoring services.
• Demonstrated ability to optimize application code and data pipelines for performance, reliability, and cost.
• Experience implementing observability, automated job recovery, and reproducible processing workflows.
• Ability to build simple developer interfaces and work directly with users to automate complex workflows.

• Strong PyTorch experience, including distributed training, data loading, checkpointing, and GPU utilization.
• Experience scaling ML training across large datasets and distributed compute resources.
• Experience integrating simulation and regression workloads into CI/CD pipelines.
• Familiarity with large-scale engineering datasets, flight-test data, calibration, or scientific computing workflows.
• Experience building compute platforms that support both classified and unclassified environments.
• Experience improving processing throughput and turnaround time through workload optimization and infrastructure scaling.

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 accommodation to complete an application, participate in the interview process, or otherwise participate in the hiring process, please contact View email address on click.appcast.io. 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.

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.