Just a list of tools that I use from time to time :)
7-Zip

Notepad++
Visual Studio Code : Free. Open source. Runs everywhere
Cmder : Portable console emulator for Windows
Rapid Environment Editor : Windows environment variables management
SoapUI : SOAP & ReST API Development and Testing environment
Postman : ReST API Development environment
WinMerge : Open Source differencing and merging tool for Windows.
mRemoteNG : is a fork of mRemote: an open source, tabbed, multi-protocol, remote connections manager.
Microsoft Remote Desktop Connection Manager 2.7
ILSpy : the open-source .NET assembly browser and decompiler.
TortoiseGit
TortoiseSVN
PuTTY
WinSCP

Bitvise SSH Server ( windows )
Bitvise SSH Client: Free SSH file transfer, terminal and tunneling
SSH.NET is a Secure Shell (SSH) library for .NET, optimized for parallelism.
Source Code Monitor
Visual Studio Code Metrics Powertool for Visual Studio 2013
HxD - Freeware Hex Editor and Disk Editor
Frhed ( Free hex editor )
Microsoft Message Analyzer
Audacity

fre:ac free audio converter and CD ripper
NirSoft Freeware Utilities for Windows
Sandboxie - now Open Source :)
Process Explorer [ To check which process holds the file and unlock it ]
IOBit Unlocker