I needed a lightweight map editor for my A* pages, where I’ve been adding some non-grid diagrams. I based this on this project. Drag the nodes. Double click a node to remove. Click a midpoint to divide an edge. Click on a polygon to switch to editing it. Drag the labels around (may not work for the current polygon) to set the “center” point.

JSON for the A* pages (automatically saved to localStorage):

output

Quirks: (1) you can’t drag the label for the active polygon because the active polygon is drawn on top; (2) the editor doesn’t show or let you edit the connections between nodes, which turns out to be a problem when you delete a node and they all get renumbered.

List of polygons (in case you can’t click on it directly):