BoxCryptor - Boxcryptor encrypts your sensitive files before uploading them to cloud storage services like Dropbox, Google Drive, Microsoft OneDrive, Box, and many others.
Sync.com - Sync. com offers a backup tool and a file sharing service, rolled into one.
Cloudfogger - Easy and secure encryption for the cloud. Provides security for all cloud storage services like Dropbox, OneDrive and Google Drive.
Zoho WorkDrive - File storage & content collaboration tool for modern teams
Mega - Secure File Storage and collaboration
Yandex.Disk - Files on Yandex.Disk won't get lost if your phone or computer breaks.