How to Open 7z Files on Mac

The .7z format compresses harder than zip, which is exactly why people use it for big downloads — and why it’s frustrating that macOS can’t open it natively. Archive Utility doesn’t know the format at all. One free app fixes that; Terminal users get a first-party tool from the 7-Zip project itself.

Double-click extraction: Keka or The Unarchiver

• Keka (free at keka.io; the Mac App Store version is a paid way to support the developer) extracts 7z and creates 7z, including AES-256-encrypted archives. If you deal with 7z regularly, this is the one to get.
• The Unarchiver (free, Mac App Store) extracts 7z along with practically every other archive format, but creates nothing. Perfect if you only ever receive.

Then make it stick, so double-clicking any 7z just works:

1. Select a .7z file in Finder and press Cmd+I.
2. Under Open with, choose your extractor.
3. Click Change All… and confirm. (Undo: repeat and choose another app.)

Both apps extract into the archive’s folder by default and never delete the original archive. Password-protected 7z files prompt at extraction; if the archive used 7z’s “encrypt file names” option you’ll be asked before even the listing appears — that’s expected, not corruption.

The Terminal option: 7zz

The 7-Zip project ships an official macOS build. With Homebrew:

# install once
brew install sevenzip
# list the contents
7zz l archive.7z
# extract, keeping the folder structure
7zz x archive.7z
# uninstall to undo the install
brew uninstall sevenzip

Use x (not e) to extract — x preserves the archive’s internal folder structure, while e flattens everything into one directory, which is rarely what you want. Extraction never modifies the archive itself, so there’s nothing to undo beyond deleting the extracted copies.

Creating your own 7z archives

In Keka: drag a folder onto the Keka window (or Dock icon) with 7z selected, optionally set a password in the same panel, and it writes the archive next to the original. In Terminal:

# create an archive from a folder
7zz a backup.7z "Project Folder"
# undo: remove the archive (originals are never touched)
rm backup.7z

When to just use zip instead

7z wins on compression ratio — often noticeably, on text-heavy or mixed content — but zip wins on friction: every Mac, Windows, and Linux machine opens zip with nothing installed. Sending files to someone non-technical? Zip. Archiving your own large folders where every gigabyte counts, or encrypting with real AES-256 for cross-platform use? 7z earns its keep. And media files (video, JPEG, HEIC) are already compressed — no archiver will shrink them meaningfully, so choose purely on convenience there.

When a 7z won’t open

• Split archives: big 7z files often arrive as name.7z.001, name.7z.002, and so on. Keep every part in the same folder and open the .001 file — Keka and 7zz x name.7z.001 both reassemble the rest automatically. Missing even one part means no extraction; there’s no partial recovery.
• “Cannot open file as archive”: the download is usually truncated. Compare the byte size with the source and re-download. 7zz t archive.7z tests integrity and names the first broken file, which tells you whether it’s one damaged entry or a dead archive.
• Instant password prompt, even to list: the archive was created with encrypted file names. That’s a feature, not damage — enter the password and everything proceeds normally.
• It’s not really a 7z: people occasionally rename files to dodge mail filters. If extraction fails outright, check the real type in Terminal with file archive.7z — it reports what the data actually is, whatever the extension claims. Rename it to match the real format and extract with the right tool.