We recommend only disabling cloud sync when you are using the Desktop App since clearing your browser's cache and local data will clear all your data! And if sync is disabled there is no copy of your data on our sync servers.
When using the Desktop App you have a copy of your data in your file system. Which is not easy to remove by accident.
Attachments are normally stored in the cloud. If you use the desktop app with cloud sync turned off, you can turn on Local attachments in the Attachments settings (☰ → Features → Attachments). These attachments stay on your computer only, so you're responsible for backing them up.
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