The Resource Description Framework (RDF) is a format for structured data that uses triples to represent information. A set of RDF triples, a.k.a. an RDF dataset, can be stored in a database or file and queried using the SPARQL query language (similar to how SQL works for relational databases).
One of the key features of SPARQL is the SPARQL Federation. This allows querying multiple RDF datasets at once using the SERVICE keyword.
I've created this tool to experiment with storing, visualizing, querying, and federating over RDF datasets. You can use it to experiment, learn, and test your own queries.
To use the tool, enter your RDF data in the Turtle format and the SPARQL query. The tool supports the SPARQL Federation, which means you can, e.g., query your own RDF data and Wikidata at the same time. Have fun!