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
Adobe Acrobat DC - Make your job easier with Adobe Acrobat DC, the trusted PDF creator. Use Acrobat to convert, edit and sign PDF files at your desk or on the go.
Google Drive - Access and sync your files anywhere
Foxit Reader - Foxit Reader is a free and light-weight multi-platform PDF document viewer.
Mega - Secure File Storage and collaboration
Wondershare PDFelement - All-in-one PDF editor