Skribl on operating systems
Windows - It's a nice tool and it's useful in the Microsoft way
MacOS - It's a nice tool and it's useful in the Apple way
Linux - It's a nice tool for everything and you can use it as you see fit, however you want it, and it's free, and you can contribute back / being a part of it.
:shrug:
Also the linux distro tree is always so cool to check out