Spine - Spine is 2D animation software designed specifically for software and game development.
Synfig Studio - Just another WordPress site
DragonBones - DragonBones is an open source project for 2D skeletal animation.
Unity 2D - Unity 2D is a powerful and feature-rich game design solution built from the ground up to fulfill every basic and advanced need of the developer.
AnimeEffects - AnimeEffects is a 2D keyframe animation tool based on deformation of polygon meshes.
Adobe Animate - Adobe Animate is a Flash, vector animation software.