Senior Ontology Engineer (AI)

Location: Poland, Portugal, or the Netherlands

Salary: EUR 4,600–6,700 gross per month; final compensation depends on experience, location, and professional growth.

Company

hirify.global is a global technology provider delivering data analytics and AI-powered solutions, including a large-scale Knowledge Graph and Identity platform for audience intelligence, identity resolution, measurement, and advanced analytics.

What you will do

• Own the end-to-end design, development, versioning, and governance of RDF/RDFS/OWL ontologies and SHACL validation frameworks.
• Translate business requirements into scalable knowledge graphs, semantic data models, derived-attribute schemas, and aggregation logic.
• Build production-grade knowledge graph pipelines with Python and SPARQL, including entity resolution, record linkage, and data enrichment.
• Co-design Databricks/Spark derivation and transformation pipelines with Data Engineering, including schemas and validation checkpoints.
• Define graph versus data lake strategies that balance query performance, storage, scalability, and refresh costs.
• Collaborate with Data Engineering, Data Science, Platform, and Product teams, mentor junior specialists, and lead technical workshops.

Requirements

• 5+ years of hands-on experience in ontology engineering, semantic data modeling, or knowledge graph development, including production ontologies at scale.
• Deep expertise in RDF, RDFS, OWL, SPARQL 1.1, SHACL, description logics, ontology design patterns, and triplestore scalability trade-offs.
• Experience building and validating graph schemas in a production triplestore such as Amazon Neptune, Stardog, GraphDB, or Jena.
• Strong Python skills for production-quality data pipelines and graph processing workflows.
• Experience with entity resolution, record linkage, or large-scale deduplication and the ability to explain modeling decisions to non-specialist stakeholders.
• English: Intermediate+ level required. A bachelor’s degree in a relevant field is required.

Nice to have

• Master’s degree or PhD in Computer Science, Information Science, Computational Linguistics, Mathematics, or a related field.
• Experience with Amazon Neptune, Stardog, data virtualization, PySpark, and Databricks.
• Knowledge of media, entertainment, ad tech, content and identity schemas, or behavioral event data.
• Experience with embeddings, vector databases, GraphRAG, LangChain, LlamaIndex, or GNN-based approaches.

Culture & Benefits

• Professional, financial, and career development supported by mentoring and onboarding programs.
• Corporate training portal with an continuously updated company knowledge base.
• Certification compensation for programs such as AWS and PMP.
• Private health insurance and sports compensation, depending on the type of employment.
• Additional earning potential of up to EUR 1,000 per month through participation in company activities, included in the annual bonus.
• Referral program and corporate events, including team parties, pizza days, and recreational activities.