Yes, you may jump, as long as the shooter does not jump over the line. You may cross the free throw line once the ball hits the rim. Typically, pros do not jump, but it is more common to see juniors jumping since they may not be strong enough to reach the basket without jumping.
Chat with our AI personalities
You can but for the sake of rhythm you may want to practice shooting free throws without jumping
Of course you can jump during a free throw but most players do not jump to have a consistency on their shot.