Senior Software Engineer - Data Infrastructure

Job Description 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 - Data Infrastructure We're looking for a hands-on software architect who can design and build Castelion's mission data infrastructure from the ground up. Our hardware generates terabytes of telemetry and test data across manufacturing, lab, and flight environments. You will be the first engineer to architect this company-wide system, from ingestion through visualization, ensuring our hardware teams, technicians, and analysts can get the right data at the right time. This role is not about wiring together existing cloud tools; it's about inventing the architecture, designing core services, and implementing the systems that will define how Castelion handles data for years to come. Responsibilities Architect and implement scalable systems for real-time and batch ingestion of telemetry, test, and manufacturing data from heterogeneous sources. Design and build APIs, storage models, and query systems for continuous time series data with rich metadata. Implement data access and visualization layers for non-software users (engineers, analysts, technicians). Define performance, reliability, and scalability requirements—and meet them with clean, maintainable code. Establish coding standards and software development best practices for infrastructure engineering at Castelion. Basic Qualifications 5+ years designing and coding large-scale distributed systems, back-end services, or real-time data platforms in a production environment. Strong programming ability in Python, C++, or similar system languages, with fluency in algorithms, data structures, and concurrency. Experience designing data storage and retrieval systems (PostgreSQL, time series DBs, OLAP engines, custom storage layers). Deep understanding of data ingestion from multiple protocols (message queues, streaming telemetry, APIs, file drops). Hands-on experience with query optimization, data modeling, indexing, and performance profiling. Strong Linux background and experience deploying services in cloud environments (Azure/AWS). Demonstrated ability to take a system from concept, architecture, implementation, to production. Bonus Points Experience building internal tools or platforms for hardware, manufacturing, or scientific data. Knowledge of telemetry data formats, time series analysis, or scientific computing. Exposure to real-time visualization frameworks (Foxglove, Grafana, or custom UIs). Leadership Qualities Bias to Action and Creative Problem Solving.

Desire and experience questioning assumptions to lead to breakthrough ideas that are implemented. Ability to bring applicable processes, concepts, or materials from other industries to achieve efficiency gains. Capable of resolving minor issues independently in development. High Commitment, High Initiative.

Passionate about Castelion's mission, proactively contributing to technical goals and preventing hardware blockers. Able to work in a fast-paced, autonomous, and demanding environment with a strong sense of accountability and integrity. Clear Communicator.

Proactively communicates blockers. Trusted to represent the company with regulators, suppliers, and stakeholders. Capable of managing relationships tactfully to achieve desired outcomes. Clear, detailed, and logical communication through emails, IMs, and verbal interactions. ITAR Requirements To conform to U.S. Government export regulations, applicants must be U.S. persons, lawful permanent residents, refugees, asylees, or eligible for required authorizations from the U.S. Department of State. Employment with Castelion is based on competence and qualifications and is not influenced by protected statuses. All employees receive long-term stock incentives, comprehensive medical, vision, and dental insurance, and four weeks of paid time off annually.

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