Nice! It looks like it uses a combination of DOM and SVG. I like how the arrows start and endpoints can be rearranged with the mouse and snap in place. The ine

Nice! It looks like it uses a combination of DOM and SVG. I like how the arrows start and endpoints can be rearranged with the mouse and snap in place. The inevitable question is why not base this on an existing library... depending on the project I'd probably reach for something like D3 or cytoscape.js to build a map like this (mostly because implementing auto layout algorithms is a lot of work to do from scratch, unless it is just for fun :-).