Spine

Spine is an animation tool focused on 2D skeletal animation for games. Images are attached to bones, and the bones are animated, so animations are stored as bone data rather than as frame-by-frame images. This keeps animation files small, reduces the number of art assets required, and allows animations to be reused across characters that look different. Animations can be blended, crossfaded, and manipulated through code for procedural effects.

The editor includes a dopesheet for timing, graph curves for interpolation, inverse kinematics and a multi-bone Pose tool, path constraints, skins, bounding boxes, meshes, free-form deformation, and skinning weights. It supports previewing animations as they will behave at runtime, importing JSON or binary data, and exporting animation data in documented JSON and binary formats, along with animated GIFs, PNG or JPEG image sequences, and AVI or QuickTime video. A texture packer builds texture atlases or spritesheets. Spine Runtimes are provided for major game toolkits and programming languages to load and render animations in games.

Spine is aimed at game developers and animators working on 2D games. A free trial is available for Windows, Mac, and Linux; purchasing Spine enables saving, exporting, and use of the Spine Runtimes.