<Rigging
Rigging Nodes (addon)

Rigging Nodes (addon)
blenderartists.org
free
RigNodes (Prototype)

RigNodes (Prototype)
projects.blender.org
free
Mantis Rigging Nodes

Mantis Rigging Nodes
nodes.tools
free
FreeIK

FreeIK
superhivemarket.com
paid
Ghost IK

Ghost IK
blenderartists.org
free
Kinematic Tool

Kinematic Tool
slephy.gumroad.com
paid
Character Physics

Character Physics
superhivemarket.com
paid
Lazy Bones

Lazy Bones
superhivemarket.com
paid
B-RigNet (deprecated)

B-RigNet (deprecated)
github.com
free
RBF Nodes

RBF Nodes
braverabbit.gumroad.com
free
RBF Drivers (old)

RBF Drivers (old)
gumroad.com
paid