Frequently Asked Questions

Yes. 7-Zip is open source software. Most of the source code is under the GNU LGPL license. You can use 7-Zip on any computer, including in a commercial organization. You don't need to register or pay for it.

Yes. The unRAR code is under a mixed license — GNU LGPL + unRAR restriction. If you distribute 7-Zip in your product, you must mention it in your documentation and respect the LGPL and unRAR terms. The 7z format SDK itself is public domain.

7-Zip typically achieves 2–10% better compression than WinZip or WinRAR for the 7z format. For ZIP format, it uses the Deflate and BZip2 algorithms and achieves similar compression to comparable tools. LZMA2 with ultra settings delivers the best possible compression ratio.

In most cases this means the archive contains headers that don't conform to the ZIP specification, or the file was created by a tool with non-standard extensions. Try the latest version of 7-Zip. If it still fails, the archive may be corrupted or encrypted with an unsupported method.

7-Zip can open (read) many formats including: AR, ARJ, CAB, CHM, CPIO, CramFS, DMG, EXT, FAT, GPT, HFS, IHEX, ISO, LZH, LZMA, MBR, MSI, NSIS, NTFS, QCOW2, RAR, RPM, SquashFS, UDF, UEFI, VDI, VHD, VMDK, XAR, Z. However, it can only create 7z, XZ, BZIP2, GZIP, TAR, ZIP, and WIM archives.

7-Zip uses AES-256 encryption for the 7z and ZIP formats. AES-256 is a military-grade cipher and is considered computationally infeasible to brute-force with current technology. For 7z archives, 7-Zip also supports encrypting file names, so no metadata is exposed without the password.

No. Due to the AES-256 encryption standard used by 7-Zip, there is no backdoor or recovery mechanism. If you lose the password to an encrypted 7z archive, the data is unrecoverable. Always store passwords in a secure password manager.

The command-line tool is 7z.exe (Windows) or 7zz (Linux/macOS). Common commands:

7z a archive.7z folder/   # Create archive
7z e archive.7z         # Extract files
7z l archive.7z         # List contents
7z t archive.7z         # Test integrity

Yes. Since version 21.01 alpha, 7-Zip ships official binaries for Linux (x86/x64/ARM) and macOS as command-line tools. There is no official graphical interface for Linux yet, but community ports like p7zip provide integration with file managers.

In the GUI, use Add to archive → Split to volumes (bytes). On the command line, use the -v switch:

7z a -v100m archive.7z folder/
This creates archive.7z.001, archive.7z.002, etc., each 100 MB in size.