I have no idea. The map I use right now is from an old campaign that I was in twelve years ago by a different GM I'm no longer with. But I sure wish I knew. I think he might've gotten it commissioned.

Or do you mean my combat maps? If so, I have a program called Dungeon Painter Studio I brought off steam. I make the layout with that, then save it as a PNG and load it into my paint program to add characters and enemies.