Boxcryptor is a security and privacy application that helps users protect their digital data with encryption. It provides an easy-to-use interface to encrypt files, folders and drives before they are uploaded to cloud storage services such as Dropbox, Google Drive and Microsoft OneDrive. With Boxcryptor, users can securely access their data from any device with an Internet connection. It also allows users to share encrypted data with external users, such as friends and colleagues, without having to worry about data being intercepted. Boxcryptor also provides users with the option to set up two-factor authentication for added security.
Basically an open source clone of BoxCryptor