Invision - Prototyping and collaboration for design teams
Synfig Studio - Just another WordPress site
Proto.io - Create fully-interactive high-fidelity prototypes in minutes that look and work exactly like your app should. Sign up for a free 15-day trial and get started.
OpenToonz - OpenToonz is an animation program that is a free software version of Toonz, the animation software...
Zeplin - Collaboration app for UI designers & frontend developers
Blender - Blender is the open source, cross platform suite of tools for 3D creation.