Is it safe to use one to, for example, save a password?
Plain-text login (such as username/password) information shouldn't be stored in localstorage, as if someone does get hold of them, they can continuously make a new session for themselves.
If you must store the password (which I would recommend not to) then you should encrypt this.
Thanks for the reply. Does that mean a local storage variable saved in one app can be read from another?
It sure can.