APPX / MSIX file format

.appx · .msix · .appxbundle · .msixbundle · package (signed ZIP) · introduced 2012 by Microsoft

What is a APPX / MSIX file?

APPX (later renamed MSIX) is Microsoft's modern Windows app package format, originally introduced for the Windows Store. It is a signed ZIP of the application binaries, an AppxManifest.xml, and digital signature blocks. MSIX adds support for Win32 desktop apps and is the Microsoft-recommended packaging format going forward.

Most readers reach this page after double-clicking a .appx file and finding their operating system unsure what to do with it. The good news: APPX / MSIX is a well-understood format with mature tooling on every major platform. It is supported in one click by mainstream archivers on Windows, macOS, and Linux.

How to extract a APPX / MSIX file

Opening a .appx file is straightforward on every modern operating system. The exact steps depend on which platform you are on:

On Windows

Locate the .appx file in File Explorer.
Right-click the file. If you have 7-Zip installed, choose 7-Zip → Extract Here. On Windows 11 the built-in extractor handles ZIP, 7z, RAR and several other formats directly through Extract All…
If prompted, pick a destination folder and click Extract.
The extracted files appear in a folder next to the original archive.

On macOS

Find the .appx file in Finder.
Install The Unarchiver from the Mac App Store, or Keka for both creating and extracting.
Right-click the file → Open With → The Unarchiver (or just double-click after Unarchiver is set as the default).
The extracted folder appears next to the archive.

On Linux

Use your file manager: right-click the archive → Extract Here (file-roller on GNOME, Ark on KDE).

On the command line, run one of:

7z x archive.appx    # works for almost any format

The files appear in the current directory.

How to create a APPX / MSIX file

To pack files into a .appx archive, you typically need an archiver that supports writing this format. Not every tool can create every format — for example, only WinRAR can create real RAR files. The sidebar lists the software known to read and write APPX / MSIX.

On the command line, the canonical create command is:

# Use 7-Zip, PeaZip, or the format's reference tool to create .appx files.

If you regularly create archives at scale, a dedicated archive automation suite can wrap this command in scheduled jobs, integrity checks, and offsite replication.

Strengths

Signed and isolated install
ZIP under the hood
Atomic upgrade and uninstall

Weaknesses and limitations

Requires AppX runtime
Less mature than MSI for enterprise

Typical use cases

Microsoft Store apps
Modern Windows desktop deployment

Technical details

APPX / MSIX uses the ZIP (DEFLATE) algorithm and is identified on disk by the magic byte sequence 50 4B 03 04. The standard MIME type is application/vns.ms-appx. The format is an open specification and is free for any use.

Frequently asked questions

Is APPX / MSIX safe to open?

Archive files are containers — they are only as safe as what they contain. A .appx from a trusted source is fine; one received from a stranger can hold malicious executables, scripts, or files engineered to exploit bugs in your archiver. Always keep your archiver updated, and never run unknown executables that come out of an archive. A safe workflow is to extract into a sandbox and scan the contents before opening anything.

What is the maximum file size?

Modern implementations support archives in the multi-terabyte range. The practical limit is your filesystem (FAT32 caps at 4 GB; ext4, NTFS, APFS, and exFAT all comfortably handle multi-TB files).

Can I password-protect a APPX / MSIX?

Some archivers can wrap APPX / MSIX files in an encrypted container, but the format itself does not always include built-in encryption. Check your archiver's documentation.

How does APPX / MSIX compare to other formats?

See our format comparison pages such as ZIP vs 7z, ZIP vs RAR, and tar.gz vs tar.xz for side-by-side feature tables.