Open ZIP File

7Z File

7Z file format is used by 7-Zip compression utility to store compressed files. 7-Zip was initially released in 1999 featuring first implementation of LZMA algorithm. Due to more advanced algorithm 7-Zip provides the best compression ratio out of its competitors like RAR, ZIP and GZ. It also has the fastest extraction speed. Compression speed is on a slower side but typically it is not very important for many applications given improvement of CPU processing speed. So, if you need an archiver with the best compression ratio and quickest extraction performance 7-Zip is your best choice.

7-Zip uses LZMA and LZMA2 as primary compression algorithms but given its extendable architecture it can also use other algorithm which include:

• PPMD – Prediction by partial matching algorithm by Dmitri Shkarin for lossless image compression
• BCJ and BCJ2 – converters for x86 and x64 executables
• BZIP2 – Burrows-Wheeler algorithm
• DEFLATE – original version of LZ77 algorithm

LZMA/LMZA2 compression algorithms are open source and licensed in the public domain. It means anyone can use, rewrite, modify, or sell this software without any legal consequences from the authors. 7-Zip utility is also open source and is distributed under GNU LGPL license.

Information in 7Z archive could be encrypted using AES-256 bit encryption. It also uses key stretching algorithm to make brute-force search for a password more complex for a hacker. 7Z also allows encrypting filenames.

You can download 7-Zip sources at 7-Zip SourceForge repository. Latest LZMA sources are available for download from 7-Zip.org SDK page.

7-Zip is available for Windows platform only, through there are several third party applications which support 7Z compression and decompression on Mac OS and Linux. These include The Unarchiver for Mac OS and p7zip for Linux and Unix.

Igor Pavlov and his team provides support for 7-Zip utility and LZMA SDK via 7-Zip SourceForge forum page.

Due to the open source and free license of 7-Zip there are many derivatives of 7-Zip on the market. Many of them have adware installed as part of their installation process. That is why it is better and safer to use original 7-Zip software from 7-zip.org.