ALZip is an archive and compression utility from ESTsoft for Microsoft Windows.

Originally ALZip was developed in 1999 as an internal application at the South Korean software company ESTsoft in response to employee frustration with using the English interface in WinZip.

The Korean interface was immediately well received and later that year ALZip was publicly released as freeware. In just over a year ALZip became the most popular zip program in Korea and by December 2001 was the top downloaded software in the country. By 2004 it had reached a 70% market share in South Korea. The popularity of the software and the ALZ archive format played a large role in earning ESTsoft a place in the Digital Innovation Awards Top 100 Companies in South Korea with the software taking special mention.

Early in its development ALZip introduced the ALZ file format to deal with file size limitations of the ZIP file format. ALZ compression has no theoretical upper limit for file sizes, as they are only limited by operating system limits or the amount of available storage. The file format has become common in Korea.