42.zip Instant

It is a tiny ZIP file, only in size, that contains an astronomical amount of data—roughly 4.5 petabytes (4,500 terabytes)—when fully uncompressed.

It uses recursive compression . The main file contains 16 zipped files; each of those contains another 16, and so on, through five layers. The final layer contains a single 4.3 GB file filled entirely with zeros. 42.zip

For a deeper dive into how this works and its modern evolutions, these posts are excellent resources: What Is a Zip Bomb? Defending Against Decompression Attacks It is a tiny ZIP file, only in