.cab

What is a .cab file?

CAB is Microsoft's archive format used in Windows installers, system updates, and driver packages.

Use caution
Type Archive
By Microsoft
MIME application/vnd.ms-cab-compressed

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What is it

Cabinet files are Microsoft's internal archive format. They're everywhere in Windows but rarely seen directly — .cab files live inside MSI installers, Windows Update packages, driver archives, and system component stores. When Windows installs an update or a driver, it's extracting from cabinet files behind the scenes.

The format supports multiple compression algorithms (MSZIP, LZX, Quantum), multi-part archives spanning multiple files, and digital signatures. It predates ZIP in Microsoft's ecosystem, dating back to Windows 95's installer. The .cab format is optimised for installation workflows rather than general-purpose archiving.

You can open .cab files with Windows Explorer (double-click), 7-Zip, or the `expand` command (`expand archive.cab -F:* destination\`). Most users encounter .cab files when downloading driver packages or Windows hotfixes. For general-purpose archiving, use ZIP — .cab is a specialised format for Windows deployment.

Technical details
Full Name
Windows Cabinet Archive
MIME Type
application/vnd.ms-cab-compressed
Developer
Microsoft
Magic Bytes
4D 53 43 46
Safety
.cab requires caution. Archive format. Contents could include drivers or system files — only extract CAB files from trusted sources.
What opens it
Windows Explorer
FREE Windows
7-Zip
FREE Windows
expand (CLI)
FREE Windows
FAQ
How do I open a CAB file?
On Windows: double-click to browse in Explorer, or right-click → Extract. 7-Zip also opens CAB files. Command line: `expand file.cab -F:* destination\`.
Why are driver downloads in CAB format?
Microsoft designed CAB for software distribution. It supports digital signatures, multi-file spanning, and efficient compression. Windows' driver installation system expects CAB-packaged drivers.
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