WinDirStat - WinDirStat is a disk usage statistics viewer and cleanup tool, inspired by KDirStat.
Bashupload - Upload files from command line to share between servers
WizTree - WizTree quickly finds the files and folders using the most space on your hard drive. It scans the MFT (Master File Table) instead of crawling the entire disk which makes it very fast.
FilePizza - Open source application used to transfer file via WebRTC and WebTorrent.
SpaceSniffer - SpaceSniffer is a freeWare (donations are welcome) and portable tool application that lets you understand how folders and files are structured on your disks.
BlackHole File Transfer - Blockchain-based file transfer. Designed for everyday use.