Sync is zero knowledge based encrypted storage, they take bitcoin and the regular payment options. Only 5gb free, but with $49 USD a year or bitcoin you can have 500gb of anonymous encrypted storage.

Their privacy policy states they keep the personal information they need to - such as info needed to process your payment and recurring payments and they keep logs of your IP address for security, improving performance and statistical information. Doesn't say how long they keep it.

Sharing via link can be password protected. Pro accounts can set expiration, set download limits and allow uploading to your links. Sharing folders requires each party to register.

Clients for Windows, Mac, ios and android.