Inverse Kinematics of a 5 DoF Robot
It can be challenging to understand inverse kinematics, so a visualization tool is beneficial. There are many physics simulators and packages, such as MoveIt or MATLAB toolboxes, that will do this visualization for you, but making your own visualization is always a sure-fire route to take.
This visualization tool was actively used for a project I worked on for a robotic manipulator. It was the platform for us to optimize the IK solver before using it on the robot.