Beyond Compare - Beyond Compare allows you to compare files and folders.
Onyx by Titanium - This website provides operating system utilities for macOS
WinMerge - WinMerge is an open source differencing and merging tool for Windows.
AVG PC TuneUp - Peak performance for your PC. Keeps it going for longer. - More Speed Turbo Mode
Meld - What is Meld? Meld is a visual diff and merge tool targeted at developers.
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?