Does cracking your fingers harm your hands ?

Not necessarily: There are varied opinions on whether cracking of the joints can cause harm. With a TMJ/TMD issue, definitely. With the hands, fingers, neck...depends. But my best answer is to stop doing it.

No: No, it has not been shown to cause any oroblems

Yikes.: There are two schools of thought over this activity. Most believe that no harm is done with the popping of the knuckles, but I've never read a study that supports that position. There has been a study that show long term popping of knuckles may cause hand swelling and a loss off grip strength, at least for some people. Go figure.