Senior Ontology Engineer

Socket.dev; Arlington (VA); On-site; USD 175,000 - 228,000; Full time

Job summary

PixelRain AI is a small, fast-moving AI company delivering an AI-powered product-lifecycle knowledge platform for a U.S. DoW customer.

You will design, build, and maintain the enterprise ontology and vocabularies, map data into them, and manage the knowledge graph with RDF stores and SHACL validation. You will also develop the governed ingestion path with provenance, connect the graph to retrieval and GenAI applications, and perform full-stack work (Python, APIs, AWS) in a small Scrum team.

Qualifications

• 5+ years of hands-on semantic-technology work (OWL, RDF/Turtle, SHACL, SPARQL).
• Experience building ontologies aligned to upper ontologies (BFO/CCO preferred).
• Production experience with a triple store (Jena/Fuseki, RDF4J).
• Strong general software engineering (Python, APIs, Git) and AWS experience.
• Familiarity with LLMs and RAG for connecting knowledge to generative apps.

Responsibilities

• Design, build, and maintain the enterprise ontology and vocabularies; map data into them.
• Build and manage the knowledge graph: RDF store, SHACL validation, SPARQL queries.
• Develop governed ingestion paths to land content in the graph with provenance.
• Carry full-stack development work alongside ontology tasks (Python, AWS).
• Work in a small Scrum team; demonstrate working software each sprint.

Skills

Semantic technologies

Full-stack development

LLMs & RAG familiarity

Tools

Apache Jena/Fuseki

RDF4J

SPARQL

Git

Python

AWS

Job description

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.

• 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.