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.
Online Image Editor - Online editor for images and animated gifs with multiple effects and tools
MyPaint - MyPaint is a fast, distraction-free, and easy painting tool for digital artists.
GIMP - GIMP is a multiplatform photo manipulation tool.
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
Corel Painter - Corel Painter is media painting software.