Spine - Spine is 2D animation software designed specifically for software and game development.
Animaze by FaceRig - Livestream or Video Chat with custom 2d & 3d animated avatars. Add backgrounds & props with the Animaze editor. Use on Twitch, Discord, Skype, Zoom, & more
Synfig Studio - Just another WordPress site
VUP - VTuber Maker & Animation & MMD/Live2D facial capture software.
DragonBones - DragonBones is an open source project for 2D skeletal animation.
Mug Life - Create 3D characters from any photo.