What is "synfig"

Synfig Studio (also known as Synfig) is a free and open source 2D vector graphics and timeline-based computer animation program created by Robert Quattlebaum with additional contributions by Adrian Bentley.

Synfig began as the custom animation platform for Voria Studios (now defunct), and in 2005 was released as free/ open source software, under the GNU General Public License.