Considering most of these are not free I guess it would be considered spam in any forum. So here lies a list of some of my favourite tools that assist my job, coming from ten years of professional experience.
Syntevo SmartGit. It can be used for free but it's cheap enough that it's worthy of purchase. Available for Windows, Windows Portable, Linux and Mac.
Scooter Software BeyondCompare. Cheap as dirt and I think it should be categorized an industry standard given its ubiquity.
WholeTomato Visual Assist X. Not as cheap as the others above but it adds to the features of VS. While VS 2019 is already quite good there are still many added functionalities, not least a grest Find Reference and a differentiated highlighting for symbols that uses different colors for read and write accesses to the symbol under the caret. Works in all VAX windows, even the Find References.
Adds snippets triggered by typed shortcuts (e.g. you may choose that when you tipe #ig it automatically creates the inclusion guard, //f the comment with long file description, etc).
Priceless if you are forced to use some old VS version, supports up to VS6, for which it is indispensable.
Baretail. The tail -f command, for Windows, in a graphic environment, with a grep + highlight interface to help in scanning files. It is shareware with optional payment, I paid for it after 6 years of free usage because it deserves all the money it can get.
GCS d--(d+) s-/++ a C++++ U+++ P- L+@ E-- W++ N+ o+ K- w+++ O? M-- V? PS+ PE- Y+ PGP t+ 5? X R+++ tv-- b+(+++) DI+++ D++ G e++ h--- r+++ y+++* Weapons extension: ma- k++ F+2 X