Paint.NET is great for Windows users that want more than MS Paint and for whom Photoshop is too expensive and Gimp is too complicated. But alas, this thread is not about Gimp alternatives.

Paint.NET is nice, but I prefer to use free software and to not use a closed source operating system from Microsoft.

Yes, I'd like to see a paint.net for Linux or mac

Pinta is a clone of Paint.NET for Linux and Mac.

It's mostly quite good and has very high feature parity. Although it can't resize a selected image portion and so i still use paint.net.

You can still get the source code for paint.net before the license change happened here: https://github.com/rivy/OpenPDN

If only it worked in Linux.

As an aside, I've tried Krita, but am too used to how things work in Gimp, particularly the shortcuts. How different is Paint.net?

paint.net is not free software.

Apples to oranges.