Full Key Codes is described as 'little utility to display code informations about each key of the keyboard. The developers know why :-)' and is an app in the Development category. There are five alternatives to Full Key Codes for Windows and Online / Web-based. The best alternative is Aqua's KeyTest, which is free. Other great apps like Full Key Codes are KeyboardTest (Paid), Keyboard Checker (Free), Keyboard Codes Display (Free, Open Source) and keyview (Free).
PassMark KeyboardTest allows users to quickly check that all the keys on their computer keyboard are functioning correctly, check the keyboard LED's, look at the internal scan codes being generated by the keyboard and measure typing speed.