Eltima has released CloudMounter for Mac OS X (http://tinyurl.com/h7zn3uy). It allows you to mount different cloud storages and web servers to your Mac as local disks. You can connect to Microsoft OneDrive, Google Drive, Amazon S3, Dropbox, FTP and WebDAV servers in Finder, as if they are located on your machine.
The main window of CloudMounter is basically a connections manager with corresponding buttons for each supported service and protocol. Just choose what you want to connect, enter your login credentials and enjoy managing your online files on a mounted drive in the Finder.
CloudMounter doesn’t store your login details. Access to cloud services is performed through their developers’ API [application programming interface], and FTP\WebDAV passwords are securely kept in Mac OS X Keychain and sent directly to the servers via SSL-encrypted channels, according to the folks at Eltima.
CloudMounter costs $29.95 for a single user license. It requires Mac OS X Yosemite or El Capitan.