Choose the Level. Enter your map's URL and click Load Map or pick one from the menu. When you see the map, click in rooms to place room numbers and drag to reposition. Contents for rooms will randomly generate as you place them. The node editor will let you edit or reroll contents.
Re-skin creatures or replace other repeating text in room descriptions and notes - there is no Undo so be careful.Replace with in Notes and all Location Descriptions.
Export dumps the data for the current dungeon into the field below. Copy and paste into an email or a file to move to another computer. Paste into the field there and click Import to load it. Careful editing in this field is possible. Save with a name on the destination computer.
To manually save and use the dungeon outside this page, copy the text of the room contents table and notes field and paste into another file, and use the Download Image button on Chrome or the right click menu to save the image as a PNG. If you need to clear all cached data in your browser for some reason, please export if you'll want to use a dungeon in DunGen again or manually save of any dungeons you care about first. DunGen saves to your browser's "LocalStorage" not to a server. Clearing all LocalStorage will wipe out any saved and edited dungeons.
Split out the notes field to separate fields, as a step towards better UI layout and data update.
Map Artists: If you have posted maps online that you would like included in the convenience dropdown menu, let me know on G+ or a comment on my Ruminations of a Geek blog post about this, either specific map names and image URLs or point me to a collection page and I'll find the URLs there. You can also reshare a G+ post with a map you want included to me. I figure on including artists' names or initials before the map titles, and then going hierarchical by the artist's name as the first level once the list gets long enough to be awkward as a single list, with the credits section below linking back to your pages.
I will be rescanning some of the maps I linked in the menu to make them a better fit here.
EA: Ed Allen
BL: British Library Flickr of free images from old books
Comments welcome at the Ruminations blog linked above or on G+. If you like hacking, take a look at the dungen_stock.js file first. It's pretty easy to customize content there. DunGen is now up on Github.