Semantic Web
Apache Jena open-source framework for working with RDF, OWL, and semantic web applications.
SPARQL 1.2 Query Language is a query language, and can be used for diverse data sources, contains capabilities for querying required and optional graph patterns along with their conjunctions and disjunctions. SPARQL also supports aggregation, subqueries, negation, creating values by expressions, extensible value testing, and constraining queries by source RDF graph. The results of SPARQL queries can be result sets or RDF graphs.
Virtuoso SPARQL Query Editor - BNE | Datos
Virtuoso SPARQL Query Editor - DBpedia
SPARQL Query Editor - CervantesVirtual - FBVMC
Datos Enlazados - Ontologías y vocabularios - FBVMC
Virtuoso SPARQL Query Editor - Europeana
EDM EUROPEANA DATA MODEL
SPARQL de EU Open Data Portal (EU ODP)
Protégé is a free, open-source platform that provides a suite of tools to construct domain models and knowledge-based applications with ontologies.
RDF4J open-source platform for storing, querying, and managing RDF data.