A system and method for opening locks, primarily door locks like the locks on hotel room doors using a handheld mobile device and a QR code. A mobile user can be provided with a QR code either via email or from a mobile phone application (App.). The QRC will be their room key. The handheld mobile device will display the QRC on its display. A QRC scanner is connected to the door lock through a processor that can decode the QRC. The processor sends a command to the door lock to open when the proper QRC is decoded.