For hosting common files it's ok. Also it is on Android too do, great to transfer files between your Windows and your phone. But if you want better security you have to subscribe a monthly offer.
Dropbox - Online Sync and File Sharing
WHMCS - WHMCS is an all-in-one client management, billing & support system for online businesses.
Google Drive - Access and sync your files anywhere
HostBill - HostBill is a powerful and flexible, all-in-one automation, billing, client management and support platform for online businesses.
Mega - Secure File Storage and collaboration
Blesta - Blesta is professional client management, billing, and support software.