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
Easy Vault - Easy Vault: Hide Pictures, Videos, Gallery, Files is an all-in-one privacy protection application designed for those who want to lock and hide their private files.
Google Drive - Access and sync your files anywhere
Folder Lock - Folder Lock is a security software that helps you to password protect files, shred files, clean history, encrypt the personal documents and much more.
Mega - Secure File Storage and collaboration
Photo Lock App - Photo Lock App – Hide Pictures and Videos is one of the best privacy protection apps developed and published by Donna Danley.