7z (7-Zip Archive)
7z is an open-source archive format that offers some of the highest compression ratios available. It supports multiple compression algorithms, AES-256 encryption, and solid archives. The 7-Zip program that creates it is free, open-source software.
MIME Type
application/x-7z-compressed
Type
Binary
Compression
Lossless
Advantages
- + Best-in-class compression ratios with LZMA2
- + Open-source format and tooling (LGPL license)
- + AES-256 encryption including encrypted file headers
- + Supports files larger than 16 exabytes
Disadvantages
- − Slower compression speed than ZIP or Zstandard
- − Not natively supported by operating systems
- − No built-in error recovery like RAR
When to Use .7Z
Use 7z when minimizing file size is the top priority — software distribution, backups, and archival of large datasets.
Technical Details
7z archives use a modular architecture supporting LZMA, LZMA2, BZIP2, PPMd, and other compressors. Solid mode compresses files as a single stream, and the format supports file headers encryption.
History
Igor Pavlov created 7z in 1999 as part of the 7-Zip file archiver. The format uses LZMA (Lempel-Ziv-Markov chain Algorithm) by default, which was specifically designed for high compression ratios.