Onyx by Titanium - This website provides operating system utilities for macOS
TinkerTool - Tinker with the hidden settings of your Mac
AVG PC TuneUp - Peak performance for your PC. Keeps it going for longer. - More Speed Turbo Mode
Glary Utilities - The No. 1 Free, Powerful and All-in-one utility for cleaning your PC
Cocktail - General purpose system modify/repair utility
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?