LOUPE
Point it at writing and it works out what is about what. It splits the source into items — passages of a text, files in a folder, records in a graph — weighs the words each one uses that the others do not, and scores every item against every other. Then you can search it, see what resembles what, and hand the result to anything that draws a graph.
Text, markdown, code, csv, json — and a graph file with nodes / links in it is read as a graph, keeping the links already in it. Everything happens in this page: nothing is uploaded, stored or sent anywhere, and there is no network call in this file. One thing is kept: the browser's handle to the last folder you opened — the permission slip, not the contents — so it can be offered back to you above. Forget it any time.