Synfig Studio is a free and opensource animation software. It allows users to create animation without need to draw each frame from scratch. Full featured bone system can create cutout animation using bitmap images or control your vector artwork.
Synfig supports a multitude of layers of various types including gradients, geometric, filters, fractal, distortions, transformations and a few others. The Skeleton Distortion layer allows to apply complex deformations to bitmap artwork. Synfig has basic features for syncing your animation with soundtrack using Sound Layer. Linux users can get all benefits of full-featured audio editors through the JACK integration.
Synfig Studio can simulate soft-shading using curved gradients within an area so that the animator doesn't have to draw shading into every single frame. There is also a wide variety of other real-time effects that can be applied to layers or groups of layers like radial blurs, color tweaks that all are resolution-independent. Other features include the ability to control and animate the width of lines at their individual control points, and the ability to link any related data from one object to another.
Synfig stores its animations in its own XML file format compressed with gzip. The files store vector graphics data, embed or reference external bitmap images, and also a revision history of the project. Synfig can render to video formats such as AVI, Theora and MPEG, as well as animated graphics like MNG and GIF. It can also render to a sequence of numbered image files in format PNG, BMP, PPM or OpenEXR. Synfig also works with HDR Imaging.