Shellcodes are small codes in Assembly language which could be used as the payload in software exploitation. Other usages are in malware, bypassing antivirus software, obfuscating code for protection and so on.
This software can be run on Windows/Linux/OSX under Python.
Why use OWASP ZSC Obfuscated Code Generator Tool
Another good reason for obfuscating files or generating shellcode with ZSC is that it can be used for pen-testing assignments.