Pencil2D

cil2D is a multiplatform open-source tool that enables you to draw and animate 2D art. Pencil2D can't compete with Flash, even though its animations are based in keyframes and different layers. Unlike Flash, when using Pencil2D you'll need to hand-draw each frame of your animation. Pencil2D allows you to create four layers: bitmap layer, vector layer, sound layer, and video layer, all of which need their corresponding elements in order to produce an animation. The version for Mac allows you to export your animation to video, something that the version for Windows is still lacking.