Data engineer in ontology and knowledge graphs

Valarian is a dual use technology company building critical tools to safeguard the future in an era of evolving global security challenges. Backed by a Series A funding round of $50m led by NEA, we are rethinking security beyond traditional military domains to address asymmetric threats that impact our technological advantage, economic strength, and democratic institutions. We provide the control infrastructure that allows government and regulated enterprise to put frontier-class AI to work safely.

• Work with product teams and domain experts to define and evolve ontologies covering organisational entities, relationships, classifications and business rules
• Build ingestion and transformation pipelines from APIs, databases, documents, files and events into canonical data models
• Implement entity resolution, deduplication and source reconciliation, retaining provenance and handling conflicting or uncertain information
• Design and maintain graph models, relational schemas and NoSQL structures, choosing representations according to query and consistency requirements
• Develop efficient queries and data interfaces for applications, retrieval services and AI tools, with traceable results
• Implement automated tests for transformation correctness, semantic constraints, relationship integrity and source-to-target reconciliation
• Preserve source permissions, classification and retention requirements through derived datasets and graph relationships
• Own model evolution and migration logic, partnering with DataOps on deployment, backfills and recovery

• Strong production Python engineering and experience building maintainable, tested ingestion and transformation pipelines
• Strong SQL, including relational modelling, transactions, indexing, migrations and query optimisation
• Practical NoSQL experience, including document or key-value modelling, indexing and consistency trade-offs
• Production experience designing, populating and querying a graph database or triple store—for example, Neo4j with Cypher, or an RDF store with SPARQL
• Practical ontology design experience: clear entity definitions, stable identifiers, relationship semantics, controlled vocabularies, constraints and versioning
• Understanding of property graphs and RDF-based knowledge graphs, including when each approach is appropriate
• Experience integrating heterogeneous sources, resolving entity identity and maintaining provenance and lineage
• Experience handling incremental updates, deletions, schema changes and automated data validation
• Ability to translate ambiguous domain requirements into documented models, useful queries and reliable data interfaces

• Equity – because you have the right to own what you’re building
• A competitive salary – because we value your unique skills
• Employer pension contributions – because you deserve a secure future
• Private health insurance - because your health is important to us
• Hybrid work setup – because everyone has different needs
• Gym memberships - because staying active fuels productivity
• Rewarding company retreats and meetups that respect your work/life balance – because we love getting to know each other
• We operate on an office first hybrid model, regularly gathering in our London office to support one another and collaborate.