ZIPX

ZIPX is a variant of the ZIP archive format that uses the .zipx extension. It was developed to extend the original ZIP format by allowing access to multiple newer compression algorithms beyond Deflate, such as BZIP2, LZMA, PPMd, and JPEG-based compression. The format is defined within the ZIP framework but encodes file data with these enhanced methods while keeping the ZIP central directory structure. As a result, ZIPX archives can offer higher compression ratios for certain data types at the cost of compatibility complexity.

Software support is uneven. WinZip has historically provided full read and write support for ZIPX archives, and some other tools such as 7-Zip and certain versions of PeaZip can extract ZIPX files and, in some cases, create them. However, many older ZIP tools do not recognize ZIPX and may fail to open or incorrectly extract files from zipx archives, leading to compatibility issues when exchanging archives with users who do not have updated software.

Because ZIPX relies on optional compression methods, interoperability depends on the implementing software. When cross-platform access is required, it is common to convert ZIPX files to standard ZIP or another widely supported format.

See also: ZIP, PKZIP, WinZip, 7-Zip.