CleanMyMac X - Clean, protect and speed up your Mac
DiskWarrior - DiskWarrior, the world's most advanced and highest rated hard disk, hard drive, and disk repair and data recovery tool for macOS, OS X and Mac OS X.
Fossils - Find and clean out all your old unused files
Data Rescue - When Apple's system recovery fails, recover any and all files with Data Rescue 3. This data rescue software will even work if your Mac's hard drive fails to mount.
DaisyDisk - DaisyDisk is a disk analyzer tool for OS X that visualizes hard disk usage and allows to free up hard disk space.
321Soft Data Recovery for Mac - The ultimate Mac Data Recovery software with RAID supported.