What is a 7Z file?
7Z is the archive format of the open-source 7-Zip program, released by Igor Pavlov in 1999. It compresses with LZMA and LZMA2, which squeeze text, source code and documents far tighter than ZIP's Deflate, and it packs files together in a solid block so that many similar files share one compression dictionary. Archives of software, datasets and backups are often a third smaller than the ZIP equivalent.
The format supports AES-256 encryption of both contents and file names, file sizes beyond 4 GB, and splitting into volumes. Its drawback is reach: Windows and macOS have no built-in extractor, so recipients need 7-Zip, WinRAR, Keka or The Unarchiver, and web uploads often accept ZIP only.
When 7Z is the right choice
Strengths
- Much smaller archives than ZIP, especially for many similar files
- Strong AES-256 encryption including hidden file names
- Open format with a free reference implementation
Limitations
- Not opened by Windows or macOS without extra software
- Solid archives need full decompression to extract one file
- Slower to create than ZIP
How to open a 7Z file
Install 7-Zip on Windows, Keka or The Unarchiver on macOS, or use p7zip on Linux. Without installing anything, Extract 7Z unpacks the archive online and lists its files; password-protected archives need the password.
How to convert a 7Z file
7Z to ZIP produces an archive anyone can open without software, 7Z to TAR.GZ or 7Z to TAR.XZ suit Linux servers, and Extract 7Z simply unpacks it. To go the other way and save space, use ZIP to 7Z.