Fav Software 2 years ago in Android Apps
SyncThing
"replaces proprietary sync and cloud services with something open, trustworthy and decentralized"
3 years ago in Free Software
FreeFileSync
backup and synchronization of folders, couldn't have a nicer GUI
About
Software I can recommend, mostly free and open source. Ignoring Mac support even where it exists in an effort to pretend Apple doesn't exist.