Does Air Explorer use external or own servers to any function?
Air Explorer never use intermediary servers.
When Air Explorer upload and download files, it doesn’t use any external server for the management of them. The files go directly from the local disk to the cloud you choose.
When the files are exchanged between two servers, the files don’t go through any external server, they pass by your computer which functions as an intermediary.
The account settings are also saved locally on your computer.
In this way, your files and configurations always are private.