https://www.synfig.org/
https://github.com/synfig/synfig/

https://wiki.synfig.org/Main_Page
https://synfig.readthedocs.io/en/latest/index.html

https://www.synfig.org/news/

2016
https://opensource.com/article/16/12/synfig-studio-animation-software-tutorial