Welkin is a graph-based RDF visualizer that works on Windows, Linux and MacOSX, by using the java WebStart. RDF is a metadata model that uses XML as an interchange syntax and has come to be used as a general method of modeling knowledge.
Welkin is an archaic english term to define the celestial sphere, the apparent surface of the imaginary sphere on which celestial bodies appear to be projected. As the authors explain: "The reference to the sky and celestial bodies is very meaningful in this context: Welkin is not meant to be a tool to discover a single RDF statement out of a thousands, but it's meant as a 'telescope' for your RDF data, a tool that lets you understand its global shape and cluster characteristics rather than the individual item".
Welkin it's thought for an audience of data and metadata analysts that need to, among other things: get a mental model and a sense of the density of connectivity of a particular dataset or dataset fragment.