I used to dungeon painter online, then I bought dungeon painter studio because I liked the software. I still use DPS for my non-totm campaigns. Both are dead and not receiving updates now, though. Source: about 1 year ago

Pyromancer Dungeon Painter The online module no longer works due to Flash dying, so you will need to download the free software. Source: over 2 years ago

Best free option I've seen is Dungeon Painter Online (though flash is gone so have to download now). Dungeonscrawl is fantastically simple for sketching a quick dungeon. I've also used Inkarnate, Pymapper and some others I forget. The wiki has some recommendations. Source: almost 3 years ago

I used this one a bit before it went download only. http://pyromancers.com/dungeon-painter-online/. Source: almost 3 years ago

It's hard to beat Inkarnate for its raw capabilities in both world generation and map/dungeon design. And it has a free option. Obviously limited, but you get what you pay for in truth. Next for me would be the (potentially pricy, but very worth it) Caeora integrated into World Anvil. The complexity you can manifest is absolutely insane. While Azgaar (and "similar" (itch.io) based tools) are without a question... Source: about 3 years ago

Maybe you could use something like Tiled (https://www.mapeditor.org/) or Ogmo (https://ogmo-editor-3.github.io/). They're meant to be level editors but you can also define custom metadata for tiles. And if these tools aren't suitable I would probably write my own simple editor. Source: about 2 years ago

All of them can, you just have to write the parser yourselves. I prefer to use Ogmo. Source: about 3 years ago