Senior Ontology Engineer

PixelRain AI is a small, fast-moving AI company delivering an AI-powered product-lifecycle knowledge platform for a U.S. Department of War (DoW) customer: governed ingestion of technical documents, an enterprise ontology and knowledge graph, and generative-AI applications that draft maintenance-planning products and answer engineering questions with citations - running in the customer's cloud environment, with an offline variant for disconnected use. Small team, real users, working software demonstrated every sprint.

Salary: 175,000 - 228,000

Active US Security Clearance Required

What you'll do

• Design, build, and maintain the enterprise ontology (BFO/CCO-aligned) and controlled vocabularies, and map source-system data into them.

• Build and manage the knowledge graph: RDF triple store (Apache Jena/Fuseki or similar), SHACL validation, SPARQL queries.

• Build the governed ingestion path so extracted content lands in the graph with provenance and confidence, and connect the graph to retrieval and GenAI applications.

• Carry normal full-stack development work alongside the ontology work - Python services, web UI, AWS.

• Work in a small Scrum team; demo working software every sprint.

Requirements

• Active Secret OR Top Secret Clearance Required

• 5+ years of hands-on semantic-technology work: OWL, RDF/Turtle, SHACL, and SPARQL.
• Experience building ontologies aligned to an upper ontology - BFO and CCO strongly preferred.
• Production experience with a triple store (Apache Jena/Fuseki, RDF4J, or similar).
• Solid general software engineering: Python, APIs, Git - able to handle full-stack tasks (web + AWS), not ontology-only.
• Working familiarity with LLMs and RAG - you've connected structured knowledge to generative applications.