RDF Grapher

RDF Grapher is a free web service that parses RDF data and renders it as a node-link diagram, hosted as part of the Linked Data Finland (ldf.fi) platform. It was built by the Semantic Computing Research Group (SeCo) at Aalto University and the University of Helsinki, with funding from Tekes (now Business Finland). The service is deliberately thin: it is a browser front end (with a documented HTTP API) wrapping two established command-line tools, Redland Raptor for RDF parsing and Graphviz for automatic graph layout and image rendering.

The data model is plain RDF triples. Each subject and object URI, blank node, or literal becomes a graph node, and each predicate becomes a directed, labelled edge, so the visual output is a faithful picture of the triple structure rather than an abstracted ontology view. Input can be pasted directly or supplied as a URL that the service dereferences, letting you visualize remote resources such as DBpedia entries. It accepts the common RDF serializations, mapping closely to the catalog's format entries: Turtle, RDF/XML, RDF/JSON, N-Triples, TriG, and N-Quads. Output is offered as PNG, SVG, PDF, PS, EPS, GIF, or JPG; the SVG in particular can be opened in a vector editor such as Inkscape to hand-tune the automatically computed layout.

The service exposes a simple GET/POST API of the form ?rdf=DATAORURI&from=FORMAT&to=FORMAT, which makes it easy to embed generated graph images in documentation, tickets, or teaching material. Its typical role in the graph-data and format-conversion world is quick, throwaway inspection and debugging: sanity-checking that a snippet of Turtle actually says what you think, or sharing a small ontology fragment as a picture.

Its strengths are zero setup, breadth of accepted syntaxes, and Graphviz-quality layout for small graphs. The limitations are equally clear. It scales poorly: even a few hundred triples produce a dense, hard-to-read image, and Graphviz static layout offers no interactivity, filtering, or querying. Large inputs must use POST because URL length is bounded, and being a hosted service raises privacy considerations for sensitive data. For programmatic pipelines or larger knowledge graphs, libraries and interactive tools such as RDFLib (Python), Jena/RIOT, and Graphviz (invoked directly) or richer converters like Zazuko RDF Conv. are usually more appropriate.