Zu3D - Zu3D is a best in the class stop animation software specially designed for educating the children.
OpenToonz - OpenToonz is an animation program that is a free software version of Toonz, the animation software...
Stop Motion Pro - Designed for the Windows PC only, Stop Motion Pro is the name of a stop motion animation platform for the professional and advanced level of clay animation, stop motion animation, pixelation and cut out animation.
Synfig Studio - Just another WordPress site
AnimatorHD - AnimatorHD is an ultra-modern and high-tech 3D stop animation platform for Windows operating systems only.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.