SDelete - Securely overwrite your sensitive files and cleanse your free space of previously deleted files using this DoD-compliant secure delete program.
CCleaner - CCleaner cleans, speeds up and frees up space on business endpoints.
Clean Master - Some users swear by it, some call it a glorified snake oil that does more harm than good. That can be said about any snake oil, but what specific brand of snake oil can boast almost a billion downloads around the world?
Glary Utilities - The No. 1 Free, Powerful and All-in-one utility for cleaning your PC
BleachBit - When your computer is getting full, BleachBit quickly frees disk space.
Avast Cleanup - Next generation tuneup and cleanup for your PC