Spine - Spine is 2D animation software designed specifically for software and game development.
Spirit - The animation tool for the web.
Synfig Studio - Just another WordPress site
Lottie by Airbnb - Easily add high-quality animation to any native app
AnimeEffects - AnimeEffects is a 2D keyframe animation tool based on deformation of polygon meshes.
Haiku Animator - Create powerful animations for any app or website