OpenToonz - OpenToonz is an animation program that is a free software version of Toonz, the animation software...
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
Synfig Studio - Just another WordPress site
Sketch - Professional digital design for Mac.
Adobe Animate - Adobe Animate is a Flash, vector animation software.
Invision - Prototyping and collaboration for design teams