The following is a list of all the tools that I use in day to day windows administration. More tools and details of each will follow in time.
Sysinternals: https://docs.microsoft.com/en-us/sysinternals/
A number of tools for different purposes.
TreeSize Free: https://www.jam-software.com/treesize_free/
Good for determining storage usage.
Advanced IP Scanner: https://www.advanced-ip-scanner.com/
Ideal for scanning subnets and finding out what exists.
Notepad++ (and it’s many add ons): https://notepad-plus-plus.org/
Useful for many reasons, including comparing files.
Putty: https://www.chiark.greenend.org.uk/~sgtatham/putty/
Light weight terminal emulator for managing devices.
Wireshark: https://www.wireshark.org/
Network traffic capture tool, I reckon I only scratch the surface with what this tool can do.
Fiddler:https://www.telerik.com/fiddler
Web debugging proxy.
MuzzaTech 