By way of analogy:

You could carry around a phone that has a simple Linux distro running on it. And while we're at it, what's the point of having a package repository? So we could get rid of that, and compile all our software from source. So the user experience is something like: SSH into your phone, curl down a source tarball for the calculator software you would like to run on your phone, and first make sure you have all of the build dependencies installed, and now make && sudo make install.

So what's the point of Android or iPhones?

Well, I'm very technically proficient, and yet I don't want to SSH into my phone and make && sudo make install. God help my non-techie family and friends. We all want to install software that has gone through at least some semblance of an audit, and we want to install it trivially, and we want that software to then run in a minimally privileged sandbox. While a "phone app" is technically "software", the distinguishing factor is that aforementioned features are implied when someone says "app".

So recap of what it's like to use a phone app:

- There's a distribution channel that makes it easy to search for and install the app of your choosing.

- The apps run in a sandbox. Privileges/capabilities are surfaced through a common setting UI: don't want the app to be able to send you notifications? You can toggle that in a way that the app can't circumvent.

Maybe you do or do not appreciate these features. But if you, like many, do appreciate these features, the a logical question is: is there anything like this but for software we want to use outside the context of our phones? And, well, if we're wanting this software to be accessibly not only on our phone, we should probably make this as maximally accessible as we can, and what could be more accessible than a browser based app -- now you're not limited to using it just from your phone (though that's possible too), you can access it from your laptop, or a friend's computer, or your gaming console's browser, or anywhere else where you can browse the web.

So that's what Sandstorm is, more or less. Trivially installable apps, where you can completely own your own data (if you're hosting yourself), and even if someone else is hosting Sandstorm you can trivially export your data, the whole app is sandboxed, you have a common dashboard for controlling each app's capabilities, etc.

Once upon a time, years ago, Sandstorm was a startup, and that startup did offer a paid hosting service as an option. However, that startup shut down a while ago and the paid hosting service went away. But the open source project lives on.

(I was the co-founder of said startup.)