Synfig

Synfig began as the custom animation platform for Voria Studios (now defunct),[5] and in 2005 was released as free/open source software, under GNU GPL-2.0-or-later.

The goal of the developers is to create a program that is capable of producing "feature-film quality animation with fewer people and resources.

[8] The software is capable of simulating soft-shading using curved gradients within an area so that the animator doesn't have to draw shading into every single frame.

The files store vector graphics data, embed or reference external bitmap images, and also a revision history of the project.

Much of the development of the tool since May 2008 has been in association with the Morevna Project, a Russian organization centered around an animation project using Synfig and other libre software and based on the folkloric characters of Ivan Tsarevich and Marya Morevna, specifically in the context of The Death of Koschei the Deathless re-invented as a science fiction anime.

Morevna Project.