I love me some Emacs and the aspect of not having one's data rolled up into some inscrutable proprietary binary is certainly appealing. However, are there viab

I love me some Emacs and the aspect of not having one's data rolled up into some inscrutable proprietary binary is certainly appealing. However, are there viable open-source programs to specifically meet this need (i.e. the daily operations of a small business)? I've seen a lot of startups around this (e.g. ipads at a lot of checkouts now for small businesses), but is there anything that allows the business to not have their data beholden to some 3rd party?