I constantly find myself wishing that there was a browser API for synced storage. I find myself wanting to make tools like this for my personal use but would like to share them for others as well. However right now there aren't many options other than standing up a database and being responsible for user data including privacy, security, uptime, backups and cost. I would love if there was some sort of option where the user could be responsible for their own storage and I can just let them access the code.

Of course the problem is coming up with a good syncing model. However I think even something simple would be good enough. This of course leaves the complexity to the app but we can let libraries step in until we find something that works well then consider standardizing that.

There are of course limitations with this model (you can't do inter-user logic like "friends") and for "sharing" you need another solution. (However this solution only needs to deal with "public" data).

I think the biggest problem though is that people will try to use it for tracking. But it would be super useful.