LASzip is a compression library that was developed by Martin Isenburg for compressing ASPRS LAS format data in his LAStools. It has been provided as an LGPL-licensed stand-alone software library to allow other softwares that handle LAS data to read and write LASzip-compressed data. The BSD-licensed libLAS and the LGPL-licensed LASlib can take advantage of LASzip to read and write compressed data.

LASzip is completely lossless. It compresses bulky LAS files into compact LAZ files that are only 7-20 percent of the original size, accurately preserving every single bit. For example, compressing and decompressing the LAS file lidar.las with laszip.exe (command-line only laszip-cli.exe) as shown below results in lidar_copy.las that is bit-identical to lidar.las. However, the small size of lidar.laz makes it much easier to store, copy, transmit, or archive large amounts of LIDAR.