There’s no single “official” converter, but several free, reliable options exist. Here are the most popular:

enthusiasts. A ZSO converter reduces file sizes while maintaining high performance, making it easier to store and play games from limited storage media like USB drives or SD cards. What is a ZSO File?

Some games (like those with lots of video) won't shrink much.

A fast, dedicated tool created by developer Danixu. It’s a popular alternative to older Python scripts, offering a more user-friendly experience for Windows users. ISO-ZSO Compressor (Batch Tool):