itch.io

The README.md file inside the download includes those instructions:

# mapsOrder.html

### Reorder maps list outside of RPGMaker's UI

* Drag and drop the file onto / or open it with a web browser (Chrome or Firefox)

* Drag and drop the mapInfos.json file from your project's data folder

* Click on a map you want to move

* Click the + next to the map you want to move above, below, or inside

* Click above, below, or inside on the various buttons.

* Watch it move!

* Click the save button, and replace mapInfo.json with the file it makes