Unity have just announced they have acquired Anima2D, a bone based 2D animation system (like Spine, Spriter, Creature, DragonBones, etc.) that works directly inside Unity. After the aquisition Anima2D was removed from the Unity Store and will be instead made available for free starting in January 2017.
Details from the Unity blog:
At Unity, we are always looking for new ways to help our developers and provide them with the best tools possible. To that end, we are excited to announce that Anima2D, a popular skeletal animation software, will be available to the entire Unity developer community for free starting in January 2017! Along with this powerful tool, we welcome one of the asset creators, Sergi Valls, into our dedicated 2D team.
Improving the 2D creation experience
We’re committed to the goal of democratizing development and Anima2D will be an important part of improving our toolset and workflow for developers who are focused on the 2D space. Anima2D’s unique approach to 2D animation and 2D character tools combined with Sergi’s experience will be a pivotal part of this effort.
You can read more about the announcement here. You can see a quick video of Anima2D in action linked below.