BoxCryptor - Boxcryptor encrypts your sensitive files before uploading them to cloud storage services like Dropbox, Google Drive, Microsoft OneDrive, Box, and many others.
Beyond Compare - Beyond Compare allows you to compare files and folders.
Cloudfogger - Easy and secure encryption for the cloud. Provides security for all cloud storage services like Dropbox, OneDrive and Google Drive.
WinMerge - WinMerge is an open source differencing and merging tool for Windows.
Mega - Secure File Storage and collaboration
Meld - What is Meld? Meld is a visual diff and merge tool targeted at developers.