During my time making video tutorials and teaching various software programs to students I have constantly struggled with finding a good tool for displaying the keystrokes and mouse buttons that I use. The tool should be free, lightweight, customizable and open source. Earlier I was quite happy with the Screencastkeys-addon for Blender but stopped using it after it got removed from the trunk of Blender and the problem with it was of course also that it was for Blender only. Since then I have tried many decent programs like KeycastOW, OSDHotkey and QiPress, but they all had some minor issues that made me search for yet another solution. Which I finally found in the latest beta-version of Carnac found here:
https://github.com/bfritscher/carnac/releases/tag/v3-beta
This tool is modern, looks good, has animations and now finally has also mouse support in the latest beta-version. I strongly recommend Carnac for the purpose of displaying key presses and mouse clicks for your recordings or streams.