A saltwater pool is not actually chlorine-free, it simply utilizes a chlorine generator (generator cell) instead of direct addition of chlorine.
Salt chlorinators are not an alternative to chlorine. Instead, basic table salt is converted into chlorine when water passes through a generator cell that turns the salt into hypochlorous acid, the same component that is produced when chlorine is added to pool water. As the water returns to the pool, it introduces the newly produced chlorine to the water.