Tech Tool Store - Tech tool store is an IT professional application which contains more than 600 free technician tools packed in a simple, fully featured interface.
TinkerTool - Tinker with the hidden settings of your Mac
Tron Script - Tron is a glorified collection of batch files that automate the process of cleaning up Windows systems.
Onyx by Titanium - This website provides operating system utilities for macOS
Autoruns - See what programs are configured to startup automatically when your system boots and you login.
Cocktail - General purpose system modify/repair utility