I offer multiple options, 1. they can open local files, option two is obviously to get them from the server every time. For most things they don't usually look

I offer multiple options, 1. they can open local files, option two is obviously to get them from the server every time. For most things they don't usually look at the same stuff multiple times. An average MRI is pretty low resolution and can fit in under 50mb (average 10mb, 50-60 for fMRI scans) of storage thus it's not to expensive to redownload it. For surface data it's even less, my average brain surface is also under 10mb. Most of my users are on University networks which helps a lot. Also applications in the chrome web store can get around the local storage limitation. I'd browsers to offer a quota system where the user can assign a max amount to their applications. That would solve those issues.