A "keygen" (key generator) is a program that replicates the algorithm used by the software vendor. There are two primary approaches developers of such tools use:

A keygen is a tool designed to generate license keys for software without authorization. While some may seek it out of curiosity or financial hardship, distributing or creating keygens infringes on intellectual property rights and harms developers' livelihoods.

Software licensing systems are designed to enforce copyright and ensure that only authorized users can access specific features. Modern software protection typically relies on asymmetric cryptography (public-key cryptography).