CarotDAV is a Simple WebDAV / FTP / SkyDrive / DropBox / GoogleDrive / Box / SugarSync client for Windows OS, available free of charge. It is also able to read GoogleDocs or IMAP.
Syncthing is a continuous file synchronization program. It synchronizes files between two or more computers in real time, safely protected from prying eyes. https://syncthing.net/ https://github.com/canton7/SyncTrayzor/releases/latest