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.
malmal - Draw together on a nearly infinite canvas with your friends or with strangers.
Autodesk SketchBook - SketchBook drawing and painting software provides designers, architects, and concept artists the tools to sketch ideas quickly and create beautiful illustrations.
DrawPile - Drawpile is a drawing program that lets you share the canvas with other users in real time.
Clip Studio Paint - The artist's software for drawing and painting.
Aggie.io - Draw a picture together with your friends in real-time over the internet in your browser.