Pencil is an open-source GUI prototyping tool that's available for ALL platforms. Pencil is built for the purpose of providing a free and open-source GUI prot…

Tupi is a software for the design and creation of 2D animation. This tool, inspired by and for animators, is being developed by an open community.

Synfig Studio (Synfig) is a free and open source 2D vector graphics and timeline-based animation software.