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Archive formats macOS handles, and the ones it doesn't

Double-clicking an archive works for some formats and silently fails for others. Here is what Archive Utility opens, what the built-in Terminal tools can do beyond it, and which formats need something else.

Double-click a .zip on a Mac and it opens. Double-click a .rar or .7z and, depending on your macOS version and what you have installed, it may do nothing, open in the wrong app, or complain.

The situation is less confusing once you know that macOS has two sets of built-in archive tools — the one behind the double-click, and a more capable one in Terminal — and they do not support the same formats.

What Archive Utility handles

Archive Utility is the app that runs when you double-click an archive. It lives in /System/Library/CoreServices/Applications/ and you rarely see it.

It handles, reliably:

  • ZIP — the universal format, and what Finder's Compress creates.
  • tar, tar.gz / .tgz, tar.bz2 — the traditional Unix formats, common for source code and software downloads.
  • gzip (.gz) and bzip2 (.bz2) on single files.
  • cpio and cpgz — rarely seen directly, except in the confusing .cpgz loop when a ZIP is damaged.
  • Apple Archive (.aar) — Apple's own newer format.

It also mounts disk images (.dmg), though that is handled separately, not by Archive Utility.

For everyday use — files emailed from colleagues, downloads from developer sites — that covers most of what you will meet.

What it does not

  • RAR — common for files shared online and from some Windows users. Archive Utility does not create or open RAR.
  • 7z — increasingly common for large or highly compressed archives.
  • Password-protected ZIPs with modern AES encryption — Archive Utility handles older ZIP encryption but not reliably the AES variants many Windows tools produce.
  • Split archives such as .7z.001, .part1.rar or .z01.
  • Older or niche formats: LHA, ARJ, CAB, StuffIt (.sit, .sitx).

Archive Utility's behaviour has shifted slightly across macOS releases, so if a format works on one Mac and not another, the macOS version is the first thing to compare.

The Terminal knows more than Finder

macOS includes tar, and on macOS tar is bsdtar, built on the libarchive library. libarchive reads far more formats than its name suggests.

In Terminal:

tar -xf archive.7z

extracts many 7z archives into the current folder. The same command works for many RAR archives, ISO images, CAB files and XAR packages.

It has real limits:

  • Encrypted archives generally fail.
  • Some RAR features are not supported, notably encryption and some multi-volume sets.
  • 7z archives using certain filters or solid-mode combinations may fail.
  • There is no progress indicator, and errors are terse.

To look inside without extracting:

tar -tf archive.7z

That lists the entries — a good habit anyway, before writing an unknown archive to disk.

unzip is also built in and handles ZIP from the command line with useful diagnostics — unzip -t tests an archive without extracting it.

Creating archives

Built-in options for creating archives are narrower still:

  • Finder → Compress makes ZIP.
  • tar -czf out.tar.gz folder makes gzip-compressed tar.
  • ditto -c -k --keepParent folder out.zip makes the same kind of ZIP Finder does, preserving macOS metadata.
  • zip -e creates a password-protected ZIP, using the older, weak ZIP encryption.
  • tar --format 7zip -cf out.7z folder makes a 7z archive — a little-known libarchive feature, without password support.

There is no built-in way to create RAR, and nothing built in creates an encrypted 7z.

Choosing which format to send

The recipient decides, not you.

  • Unknown recipient, any platform: ZIP. Everything opens it.
  • Mac or Linux user, preserving permissions and symlinks: tar.gz.
  • Large, compressible content, recipient can open it: 7z usually produces a smaller file than ZIP.
  • RAR: only if the recipient insists. Creating it requires the proprietary WinRAR tools.

When you need more than the built-ins

The Terminal route works when you are comfortable with it and the archive is ordinary. It is less pleasant for encrypted archives, large jobs you want to watch, or when you want to know what an archive will do before it does it.

What Ziploom does

Ziploom is an archive utility for Apple silicon Macs that covers the gaps above in a normal Mac window. It extracts RAR, ZIP and 7Z, with optional password support, and creates ZIP and 7Z. It does not create RAR.

You choose how existing destinations are handled, follow progress in real time, and reveal completed output in Finder. Before files are written, safety checks cover unsafe paths, symbolic links, suspicious compression ratios, oversized jobs and available disk space.

All archive processing stays on your Mac, with no accounts, analytics, advertising, telemetry or network features.

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