A fastening system for a zipper is disclosed which includes locking or interlocking first and second zipper pull tabs. A first zipper pull tab comprises a first base, a hook extending from the first base, and a moveable gate coupled to the first base. A second zipper pull tab comprises a second base, a cover coupled to the second base, and a post extending between the second base and the cover. For interlocking, the moveable gate and hook are further coupled around the post to provide the interlocking configuration of the first and second zipper pull tabs. The first zipper pull tab may be utilized separately from the second zipper pull tab, such as to lock to a coupling ring or another component of a carrying bag.