Abstract: Locking device is disclosed for parcel boxes or lockers. The device comprises a user operable handle and a lock mechanism comprising a motor to rotate a pinion to move a rack attached to a handle-blocker and to a deadbolt. The handle-blocker controls transition of the user operable handle between open and closed positions due to movement of the rack, and simultaneously the deadbolt is configured to move between locking and unlocking positions. In the closed position, the handle-blocker and the handle-body have a linear connection with each other and in open position this connection is lost. The handle may be activated by tapping the handle-cover, or by using an RFID, NFC or by mobile technologies. A method to operate opening and closing a parcel box locked with the locking device allows one or more users to access the parcel box via software application paired with the device.