What are some alternatives?
When comparing Photopea and Paint.NET, you can also consider the following products
GIMP - GIMP is a multiplatform photo manipulation tool.
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
Krita - Krita is a professional FREE and open source painting program. It is made by artists that want to seaffordable art tools for everyone. Concept art. texture and matte painters, illustrations and comics.
Affinity Photo - Affinity is the imaging and design suite for creative professionals exclusively for Mac.
MyPaint - MyPaint is a fast, distraction-free, and easy painting tool for digital artists.
Pixelmator - Pixelmator is an image-editing application for Mac and iPad.