What rigging and animation tools are there?

I know there is A.R.T., but it’s maya only. I wonder about alternatives. I’m mostly interested in those that are easy to use (no need to be very feature rich) and if not free at least indie priced. Bonus if it’s well integrated with UE4, but you can list any solution you know.

Blender is free.

and MayaLT is is 30 euros month. ART doesn’t work (it is a pity because look very good) , but can use Human IK “out of the box”.

Also if you use Blender and want to animate humans the MakeWalk addon (which is part of the MakeHuman project) can be used to retarget mocap data (which you can then refine if you want). I’m currently experimenting with streamlining the MakeHuman->Blender/MakeWalk->UE4 pipeline.