Is the data that you input into the online customization tool saved on our servers?

Yes, the data you input into the online tool is saved on our servers. If you want to keep your data private from us, you will need to manually edit the mapdata.js file and host your own map files. 

Note: We don't assert ownership over user map data. When users provide us with data they are just giving us the right to store that data on their behalf for the purposes of customizing and displaying a map.