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.
GUI client for Small Google Drive Google Drive based on the Small Electron Electron . https://liberodark.github.io/ODrive/
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