What would be the best way to generate custom maps for use with an algorithm like Dijstra's or A*? I have seen some methods using various game level editors to

What would be the best way to generate custom maps for use with an algorithm like Dijstra's or A*? I have seen some methods using various game level editors to output to a grid, but is there an easy way to draw custom maps, such as indoors locations, and create your node map with additional JSON data visually?