.app bundle file format

.app · directory bundle (not a real archive) · introduced 1989 by NeXT / Apple

What is a .app bundle file?

A macOS .app is not an archive at all — it is a directory the Finder treats as a single icon thanks to the Bundle bit. Right-click → Show Package Contents reveals the Contents/MacOS executable, Contents/Resources assets, and Contents/Info.plist metadata inside. Because it is a folder, you cannot email a .app directly; you ZIP it first.

Most readers reach this page after double-clicking a .app file and finding their operating system unsure what to do with it. The good news: .app bundle 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 .app bundle file

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

On Windows

Locate the .app 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 .app 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.app    # works for almost any format

The files appear in the current directory.

How to create a .app bundle file

To pack files into a .app 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 .app bundle.

On the command line, the canonical create command is:

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

Trivial to inspect
Cleanly uninstalled by deleting

Weaknesses and limitations

Not a single file — needs zip for transport
Loses bundle bit when moved through some systems

Typical use cases

macOS application packaging
Drag-to-install distribution

Technical details

.app bundle uses the None (folder of folders) algorithm and is identified on disk by the magic byte sequence (no magic — directory). The standard MIME type is application/x-apple-app-bundle. The format is an open specification and is free for any use.

Frequently asked questions

Is .app bundle safe to open?

Archive files are containers — they are only as safe as what they contain. A .app 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 .app bundle?

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

How does .app bundle 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.