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
FileCenter - Scan & organize documents with our paperless scanning management software. Perfect to organize & manage any kind of file. ✔ Try FileCenter FREE today!
Google Drive - Access and sync your files anywhere
DEVONthink - DEVONtechnologies develops DEVONthink, DEVONagent, and other Mac and iOS apps for document and information management and web research.
Mega - Secure File Storage and collaboration
PDFKeeper - Open Source PDF Document Storage Solution