Pixor for…
Your tools
Blender
Model and animate in Blender, send to Pixor in one click.
Godot
SpriteFrames for AnimatedSprite2D, normal maps for 2D lights.
Unity
Sprites through the Aseprite importer, or PNG and JSON.
Aseprite
Touch up by hand, re-bake, keep your paint.
GameMaker and others
Strips, JSON and every other format.