Download of MasterKing 2.3 was on the developer's website when we last checked. We cannot confirm if there is a free download of this software available. The program is included in System Utilities. This software is an intellectual property of HPC, Inc. According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software.
From the developer:
MasterKing® creates superior master keying systems faster than ever before. Enter some basic information and MasterKing® will generate your systems quickly and easily! MasterKing® eliminates transposed or repeated numbers, as well as uncuttable keys. Manually writing master key systems can be very time consuming and error prone.
You may want to check out more software, such as MyGPS, which might be similar to MasterKing.