Usually to Documents folder or the Appdata folder.
Viewing post in Cloud saves across devices
A quick update: I have almost finished a first beta version of it. The server is done, while the client is almost finished. I still have to decide how to make it fool proof. (that is, how to decide if I have to overwrite the savefiles on the directory or just save them).
I think I can start to test it by the end of the week if I have enough free time.
App and Server are done. I need to test the restore part of the process to be sure it works.
There is also a backup functionality for now, just in case we screw up :-)
Note that for now there is no better way to force the user to start the app before doing anything and after that. It's a push-pull functionality. You need to push your changes to the cloud and then pull them elsewhere before using it.
In the future I'd like to be able to use my tool to start the game directly so that you don't have to do much. It might be possible to start it before itch.io App, but you still need to configure which saves have to be sent to the cloud.
It's also worth of note that it is not only for itch.io. It will work with any game/app, as long as it's known where it saves and I know about it.
I'm going to add some more info on my page and maybe open a new thread on the forum soon.