Just as the Poster API supports HTTP POST, the JumpMap API now supports the same capability and there's a demo page that lets you upload files or copy/paste your own sector data into a form. Note that neighboring sectors appear empty if your jump map is extends past the edge of a sector.
I've also done some substantial refactoring of the guts of the rendering and styles code, which may help site stability a little bit. I found/patched a bug in the PDFSharp rendering library along the way. Ideally this hasn't changed anything, but please let me know if something suddenly renders differently (color, position, style) or has disappeared - it's not intentional!