Stacks works on top of a local folder so you can control your data and no third-party service can see your data, this way the software guarantees the privacy of your data. 

You could decide you want to sync Stacks folder with a cloud service of your choice when you want to access Stacks data also in others laptops. For example, if you want to sync the data between your Macbook Pro and your iMac or your desktop PC. 

To achieve this you have 3 options: