BoneSmith

BoneSmith is a 2D skeletal animation studio for game developers: rig 2D characters with bones, pose with FK dragging and two-bone IK, animate on a keyframe timeline with easing and onion-skin, and export Spine JSON, PNG sprite sheets, and animated GIFs. 100% offline.

Rig sprite parts Spriter-style, pose with FK dragging plus two-bone IK, and animate on the keyframe timeline with easing curves and onion-skinning. Start from 4 starter rigs (Knight, Slime, Bird, Robot).

The free demo includes rigging, posing, and animation with demo limits (8 bones, 1 animation, sprite-sheet export capped at 8 frames; Motion Retarget and Spine JSON/GIF export locked).

The full BoneSmith Pro ($9.99 one-time): https://theluckyduck666.itch.io/bonesmith-pro — unlimited bones and animations, Spine JSON (3.8) and animated GIF export, and Motion Retarget to steal any animation from one rig for another.