Spine - Spine is 2D animation software designed specifically for software and game development.
Synfig Studio - Just another WordPress site
Live2D Cubism - Live2D is the world's first drawing technology to enable 3D rendering of 2D images.
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 (formerly Flash Professional) - An animation tool that used key frame animation for games and movies.