GeckoLib is an animation engine for Minecraft mods, with support for complex 3D keyframe-based animations, numerous easings, concurrent animation support, sound and particle keyframes, event keyframes, math-based animations, and more. Available for all major modloaders.
mods.toml in 4.2:
mods.toml in 4.2.4 - so GeckoLib does not load and throws an error that GeckoLib is missing