Book Keeper uses Dropbox to Sync company file. You can sync your data online and view on other devices.
But Book Keeper is not online software, it is offline software.
That means you can sync your data, on other device Dropbox will have all your data ready to be viewed but to view it, you need Book Keeper Software.
Let's take an example, you know .XLS file, it is Excel file.
You can carry XLS file in Pen Drive or Memory Card or Email, but to open it, you need Microsoft Excel.
Same way, you can Sync Book Keeper Company file or Copy in Pen drive or some other device, but to view it, you need Book Keeper Software.