Synfig Studio
=============

https://synfig.org/

Synfig Studio is a free and open-source 2D animation software, designed as
  powerful industrial-strength solution for creating film-quality animation
  using a vector and bitmap artwork. It eliminates the need to create
  animation frame-by frame, allowing you to produce 2D animation of a higher
  quality with fewer people and resources.
  
  Features:
  
  - Can manipulate vector and bitmap artwork
  - Automatic tweening (independent from FPS)
  - Multitude of layers of various types (geometry primitives, shapes,
  gradients, fratals)
  - Full-featured bone system
  - Filters and effects for compositing (blurs, distortions, color
  manipulation, masks)
  - All color operations use High Dynamic-Range Imaging (HDRI)
  - Pentablet-friendly tools
  - Sound support
  - Linking data on file- or parameter-level
  - Automatic animation using mathematical functions
