It's just an Express app, so you can use whatever datastore you like — create a `routes/api/some-endpoint/[thing].js` file and export a request handler that int

It's just an Express app, so you can use whatever datastore you like — create a `routes/api/some-endpoint/[thing].js` file and export a request handler that interacts with your database of choice (or local files, or whatever). Or serve your data from a different app altogether. There are so many possibilities here, depending on the requirements of your app, that it would be folly for a framework like Sapper to dictate how you solve this problem — instead, it gives you the tools to easily solve it yourself.