The pull up is one of my favorite bodyweight exercises. Great for building strength in the arms and back. But what happens when it gets too easy?
Slow down to remove all momentum (although you are doing this already right?!)
Hold the top position for longer
Don’t pause in the bottom position, just pass straight through
Overload a single arm (e.g. archer pull ups)
Attach extra load to a weights belt
Use an adjustable weighted vest as pictured below
Personally I like the latter combined with 2 and 3. No need to relearn the move or add unnecessary complexity. Simply strap on the vest, perform the pull ups as you always have and over time add more and more weight to the vest. Classic progressive overload.
Try it and see!