The Game Genie Encoder/Decoder is a simple program which can decode and encode game genie codes for Nintendo, Super Nintendo, Genesis, Game Boy, and Game Gear game genies.

There are three versions. The original Java version which was designed to run in a web browser (although plugin support for that is now deprecated), a C++ version using Qt, and a JavaScript version that can run in a browser. If you're unsure of which version to you, pick the JavaScript version if you're using a newer browser (IE11+, Chrome, Firefox, et. al), and the C++ version if you're not.