WinDirStat - WinDirStat is a disk usage statistics viewer and cleanup tool, inspired by KDirStat.
Drive Manager - Drive Manager has been written to help you easily identify drives which are of the same type.
TreeSize - TreeSize tells you where precious disk space has gone to.
Stats - Simple macOS system monitor in your menu bar.
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.
Time Machine - Time Machine is the breakthrough automatic backup that’s built right into Mac OS X.