When downloading tools, always ensure they are from trusted sources, as modding tools are sometimes flagged by antivirus software. The ".NET" version of the extractor has been discussed in public forums for over a decade. If you'd like, I can: Tell you the extractor.

Note: specific layout varies by implementation/version — reverse-engineering or specification is needed for full compatibility.

svalencius/pk2-reader: React powered website to ... - GitHub

To understand the importance of a PK2 extractor, one must first understand the nature of the archive itself. Much like the standard .zip or .rar formats used in general computing, a .pk2 file functions as a compressed folder. It stores the game’s assets—3D models, texture maps, sound effects, and server configuration data—into a single, streamlined package. This compression serves a dual purpose: it protects the data from accidental user modification and significantly reduces the loading times by minimizing the number of file requests the hard drive must process. However, unlike standard compression formats, .pk2 is not open-source; it is a locked box designed to keep the user out.