OpenToonz is an animation program that is a free software version of Toonz, the animation software used by Studio Ghibli, amongst others.
Synfig is a free and open-source, industrial-strength, vector-based 2D animation app designed for producing feature-film animations. It eliminates the need to create animations frame by frame. It is available for Windows, Linux, and macOS.
Enve is a free and open-source 2D animation app. It can create both vector and raster animations and even use sound and video files. It has been created with flexibility and expandability in mind.
Create beautiful 2D motion graphics and vector animations for any platform in matter of minutes.