It's the digital equivalent of a sledgehammer and crowbar. Whether you have large files you need to attach and send via e-mail, upload or download through the internet, or archive or transfer onto CDs, hard drives, or flash memory devices, a compression utility is a helpful friend that can save space and reduce upload and download times.
How Small Can You Go?
The full-featured 7-Zip unpacks and packs compressed files in a variety of conventional formats and offers advanced options to adjust compression levels to your liking. It works in Windows versions 98 through XP and comes in a command-line version for Linux and Unix users. Furthermore, the program supports some 63 languages.
7-Zip also offers its own high-compression file format called 7z that is based on LZMA compression, supports AES-256 encryption, and includes self-extraction capabilities. Of course, if you're working with others, they'll also need to be using 7-Zip in order to compress and extract files in the proprietary 7z format.
Aside from its own format, 7-Zip additionally packs and unpacks files in ZIP, GZIP, and BZIP2 formats, as well as TAR, which is often used on Unix and Linux systems. As a result, while the 7z format has some key advantages, you can still use 7-Zip to work with compressed files from others who aren't using 7-Zip.
7-Zip also provides unpacking capabilities for RAR, CAB, ISO, ARJ, LZH, CHM, Z, CPIO, RPM, DEB and NSIS file formats. A new extension to the ZIP format supports strong (AES) encryption, which will be supported in the next official release of 7-Zip. Interest users can evaluate this feature now in the most recent beta versions of 7-Zip.
7-Zip comes with its own graphical file manager that looks much like Windows Explorer and works much the same way. It allows you to easily and intuitively perform its many functions (copy, delete, extract, add, etc.), as well as access and set options and work with any archived file or sets of files in a folder.
To create an archive you simply select a file, set of files, or entire folders and click the "add" button. The interface is mostly comparable to that of WinZip and anyone with minimal computer experience will have no problems using the program.
7-Zip may be used in commercial applications, but developers must specify in their documentation that 7-Zip was incorporated and licensed under GNU LGPL, as well as provide a link to the source code at the 7-zip web site. Developers can also change 7-Zip's code or write a wrapper for 7-Zip code and compile it into DLLs.
In testing, we found 7z archives to be approximately 30 percent smaller in the best cases than those that the program created in Zip format. 7z files did take longer to create than those in the Zip format, and this was the case whether 7-Zip itself was creating the Zipped file or PKZIP or WinZip were used to create the Zip files.
As one would expect, final compression sizes varied with the types of files archived. For example, MP3 files yielded minimally smaller compressed files while data files from Office applications and image files yielded smaller file sizes with more compression in the 7z format. Compared against Zip files created by PKZip and WinZip, Zip files created in 7-Zip were only minimally smaller, with a compression ratio that averaged about three percent in the best cases.
During testing, 7-Zip did an admirable job of unpacking compressed files in other formats. We encountered a few older ZIP files that 7-Zip could not extract. According to the publisher, these problems are typically the result of files with incorrect headers.
While 7-Zip won't open archives with incorrect headers, some ZIP programs apparently ignore these errors. In these cases, the developer suggests that users find and use the program that originally created the Zip file.
The price, free, can't be beat. Another plus, you don't have to register the program to use it. However, you're strongly encouraged to make a donation of $20 US to support further development of 7-Zip. Donations are accepted via credit card, PayPal, wire transfer, or check.
7-Zip is competitive with the other compression programs and compatible with their file formats. Plus it's easy to use and supports its own compression format that may, depending on the type of files, save even more space. What is there not to like?
This article was first published on WinPlanet.com.