The .YZ1 file extension was created by a Japanese company for use with the DeepFreezer file compression software. The freeware application was last released in 2000 and was compatible with Windows and Linux operating systems. The YZ1 provided the capability to add password protection to an archive file created. The format failed to capture a competitive market share and is rarely used.
Like other compression file types, the YZ1 takes a group of files and saves them under one filename. The YZ1 file type uses compression similar to that of Zip. Based on Huffman coding, it also makes use of LZ77 system. Compression and decompression both occur at good speeds.