Animation tool for 2D animation

Hello everyone,
do you know some good 2d animation tool which works well with unity?
We want use bone animations, so far we tried unity 2d animations but it's not
working very well bones keep disappearing and for every animations we must
update our character so it's going very badly and our animator is desperate.

 

If you mean you're going to bake your animations, then you have a lot of options. From Spine to Live 2D. It's impossible to advice something specific without knowing what exactly you're animating, and how you do that.
But be aware that, despite Animation 2D package is indeed yet unpolished and animation clips depend on your scene hierarchy, nothing so far beats Unity's procedural animation abilities. I've tried everything, including overpriced Spine, and I never got such good and organic motion as in Unity without laborious work.

 

I can't exactly say considering how broad the term is. Interpolation between key frames is also sort of procedural animation and this is exactly what we do when we have bones and IK at our disposal. Add to it some creativity with PerlinNoise, physics, Animator layers, blending trees and you'll get life like results with barely any efforts spent on actual animation.