Kipping pull-ups are popular among CrossFitters, who get a lot of flak for them because kipping pull-ups apparently aren't "real" pull-ups. But you may be surprised, they're a legit exercise.
If you watch people do kipping pull-ups, it looks like they're wildly swinging their body up and down and doing the very things that we tell you not to do in a standard pull-up. They're simply using carefully choreographed hip snaps and body swings to build momentum and reduce the effort needed to pull up to the bar. Notice, too, that the body moves in a curved fashion, not in a vertical path like in a strict pull-up.
As the video explains, make sure you lead the swing with your chest and shoulders, not with your legs. Also, power for the kipping pull-up comes from coordinating your hip movements. That said, kipping pull-ups won't help you build strength the same way strict pull-ups do, but they do help you develop better coordination, proper timing, and power. Just because you can do a strict pull-up doesn't necessarily mean you can do a kipping pull-up, and vice versa.
How To Do a Kipping Pull-Up [CrossFit RVA]