Semantic Engineer

About Cognizone

Cognizone is a Brussels-headquartered company specialized in semantic technologies, knowledge graphs, and linked data. We help European institutions (Publications Office of the EU, European Union Agency for Railways, DG EMPL), national administrations (Switzerland, Luxembourg), and private-sector clients turn complex, fragmented data into well-modelled, queryable, machine-readable knowledge.

Our active engagements include the CORDIS data services for the Publications Office in Luxembourg, the ERA register of railway infrastructure (RINF+ / REG+), LINDAS (the Linked Data Service of the Swiss Federal Administration), and a growing portfolio of agentic-AI-with-KG initiatives.

We are growing the Greece team (Athens / Thessaloniki), which already contributes hands-on expertise to several of our flagship projects.

The role

We are hiring a Semantic Engineer to join one of our delivery teams on a European institutional project. You will work hands-on with RDF, OWL, SPARQL, SHACL, and SKOS on production knowledge graphs that real users and downstream systems depend on every day.

You'll be embedded in an experienced team — collaborating with ontologists, senior engineers, and project managers — with plenty of room to learn, ask questions, and grow into more senior work over time.

Concretely, you will

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Implement ontologies and SHACL validation pipelines for production knowledge graphs

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Build and evolve data-to-RDF mapping pipelines feeding triplestores like GraphDB or Virtuoso

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Write and optimize SPARQL queries that power APIs, search, and analytics

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Contribute to technical discussions, design choices, and code reviews within the team

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Document your work clearly (specifications, design notes, technical handover)

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Participate in client meetings and workshops alongside senior team members

What we ask

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Bachelor's or Master's degree in Computer Science, Information Science, Software Engineering, or a related field — documented equivalent professional experience also accepted

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5+ years of total professional / IT experience post-graduation

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3+ years of hands-on experience on semantic web / linked data / knowledge graph projects, backed by concrete projects on your CV

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Solid working knowledge of the W3C semantic stack: RDF, RDFS, OWL, SPARQL, SHACL, SKOS

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Experience with at least one triplestore in production (any of: GraphDB, OpenLink Virtuoso, Apache Jena Fuseki, AWS Neptune, Stardog) — comfort with one is enough; we'll help you ramp up on others

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Familiarity with ontology engineering using Protégé or a similar editor

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Backend programming proficiency in Java or Python (either is fine)

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Comfort with REST APIs and Git

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English at C1 level — fluent, written and spoken, comfortable in team meetings and client calls

What sets candidates apart (nice-to-haves)

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Hands-on experience with declarative RDF mapping (RML, R2RML)

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Experience with Apache Jena, GeoSPARQL, DCAT / DCAT-AP, or PROV-O

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Exposure to CI/CD environments (GitLab CI, Azure DevOps, Jenkins) and Docker

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Experience integrating LLMs / agentic AI with knowledge graphs

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Familiarity with Elasticsearch for hybrid SPARQL + full-text search

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French or German at B2+ (useful for our Swiss, Luxembourgish, and French client engagements)

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Open-source contributions or publications in semantic web / KR / AI

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Domain familiarity with railway, transport, public administration, scientific research metadata, or labor-market data

What you get

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A role on a focused, technically deep team that genuinely owns its stack — no body-shopping, no random project placements

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Hybrid working setup — 2 days per week in our Athens office (collaborative, social, lunch with the team), 3 days remote, with flexible hours

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Direct involvement in EU-institution and European government projects with real public impact and long time horizons

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Real room to grow — toward senior engineering, solution architecture, or ontology specialization, depending on where your interests take you

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Mentorship from a team of senior semantic engineers and ontologists already on the project

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Occasional but light travel — Brussels visits mainly

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Competitive compensation aligned to the Greek tech-engineer market with European exposure

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A stable, 11-year-old company with a clear technical identity in the linked-data community

How to apply

Apply directly through LinkedIn with your CV (Europass format preferred, but any clean format is fine for first contact). A short note about a semantic-web / KG project you worked on, what your role was, and what you learned from it will help us hit the ground running in the first conversation.

We review applications on a rolling basis. Strong candidates can expect a first conversation within one week of applying.

A note before you skip past: if you find yourself excited by this role but unsure whether you tick every single box — apply anyway. The "nice-to-have" list is exactly that, and we'd rather meet a curious, motivated engineer with a strong W3C core than a perfect CV match who isn't excited by the work. We take CVs as a starting point for a conversation, not a checklist.

Cognizone is an equal-opportunity employer. We welcome applications regardless of gender, age, ethnicity, national origin, religion, disability, or sexual orientation.