Bone manager is a free addon for Blender 3D that helps to organize groups of bones and make working with them clearer and more understandable.

I use this addon in all my rigs, from characters to procedural models with a complex interface. For each such work, I attach CSS files, which are required for this addon to work correctly.

You can download it on Gumroad for free by putting 0 in the price field. But you can consider a monetary reward for the author.