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.
Dubsado - Dubsado is flexible — it gives you 5 (now 6!) ways to add new leads. Best of all, 5 ways are automated.
Dropbox - Online Sync and File Sharing
Harlow - Harlow helps freelancers get organized, save time, and look professional with automated invoicing, proposal templates, and much more—all from one centralized hub.
Google Drive - Access and sync your files anywhere
Hecticapp.com - Hectic is a single digital workspace with all the tools needed to start, manage and grow a freelancing business, with a built-in personalized community to help freelancers connect with others, develop and refine their craft and get help from experts.
Mega - Secure File Storage and collaboration