DrawPile - Drawpile is a drawing program that lets you share the canvas with other users in real time.
MyPaint - MyPaint is a fast, distraction-free, and easy painting tool for digital artists.
PaintTool SAI - Learn to draw in different ways.
Microsoft Paint - Paint (formerly Paintbrush) is a simple, ultra-basic graphics painting program that is included...
Excalidraw - Excalidraw is a whiteboard tool that lets you easily sketch diagrams that have a hand-drawn feel to them.
GIMP - GIMP is a multiplatform photo manipulation tool.