 7-zip is an open source file archiver, or an application used to compress files. 7-zip operates with the 7z archive format, but can read and write several other archive formats. the program can be used from a command line interface, graphical user interface, or with a window-based shell integration. 7-zip began in 1999 and is developed by igor pavlov. the cross-platform version of the command line utility, p7zip, is also available. 7-zip is open source software. most of the source code is under the gnu lgpl license. the unrar code is under a mixed license: gnu lgpl + unrar restrictions.pavlov, igor. 7-zip. retrieved 2012-10-31.pavlov, igor. license. 7-zip.org. retrieved 2012-10-31. ==formats== ===7z===  by default, 7-zip creates 7z format archives with a .7z file extension. each archive can contain multiple directories and files. as a container format, security or size reduction are achieved using a stacked combination of filters. these can consist of pre-processors, compression algorithms, and encryption filters. the core .7z compression uses a variety of algorithms, the most common of which are bzip2, lzma2, and lzma. developed by pavlov,
1999_software File_archivers Free_data_compression_software Free_file_managers Free_multilingual_software Free_software_programmed_in_C Free_software_programmed_in_C++ Portable_software Software_using_the_LGPL_license Windows_compression_software