Oh yes, and its a god-send, I couldn’t live without it lol 
Thing is I don’t trust these services - Google GMail has just been hacked (user level phishing) so that’s the sort of thing that we should all worry about.
Yep, unfortunately, that is the drawback of convenience and any Cloud service that stores data. All are prone to hacking. Saying that, anything is prone to hacking, just depends how much of their life the hacker wants to spend on achieving their goal.
I havn’t come across any software that would provide a similar solution off-cloud (at least in a web browser). Although, Googled this, has a “cloud sync” feature: https://www.enpass.io/apps/linux/