There is no way to save/load a village, sorry. In the next update it will become possible to get a seed of a village to regenerate it later.
Hi Watabou, what is the JSON export used for? Thought that would be to import and closed my village only to find out I was wrong.
Edit: Found it. Would still love to see an import back into this generator when/if feasible.
"Currently you can only load those JSON's in City Viewer. I don't plan to add a save/load functionality in this generator."