ZIP vs 7z vs RAR: differences, encryption and how to open RAR on Mac

Formats, encryption and cross-platform pitfalls, explained for anyone who just received an archive they cannot open

한국어 버전

Updated 2026-10-25 · By SETLOG · 8 min read

The two jobs of an archive

An archive does two separate things: it bundles many files and folders into one, and it shrinks the data. ZIP and 7z do both at once, while tar only bundles and leaves shrinking to a separate compressor such as gzip, xz or zstd, which is why Linux files carry double extensions like .tar.gz. Knowing this lets you guess what an unfamiliar extension does.

In practice the problem is rarely the compression ratio. It is whether the recipient can open the file, whether non-English file names survive the trip, and whether the recipient's tool supports the encryption you chose. This guide tabulates the formats, shows how to open a RAR file on a Mac, and then covers encryption and cross-platform traps separately.

ZIP vs 7z vs RAR: format comparison

A spec ceiling such as 7z's 16000000000 GB is not a practical limit. The real limits are the file system, available disk space and the recipient's tool. A ZIP over 4 GB needs a tool that understands ZIP64, which is a frequent problem with older software.

How to open RAR on Mac

This is the question that sends most people to this page. Double-clicking a ZIP on a Mac works because the built-in Archive Utility handles it. Double-click a .rar or .7z and macOS has nothing to offer, because those formats are not part of the system tools. You have three realistic options:

1. Use an app that supports RAR. A third-party extractor such as Zipda (described below) opens the archive, lets you look inside, and extracts it to a folder you choose. This is the quickest route when you receive an occasional RAR attachment.
2. Use a command-line tool. Open-source tools can unpack RAR and 7z from Terminal. This suits developers, but it is awkward for one-off files and for password-protected or split sets.
3. Ask for another format. If the sender can re-send as ZIP, a Mac opens it with no extra software. This is the simplest fix when you can reach the sender.

Whichever route you take, remember that RAR is a proprietary format: creating RAR needs the official tool, so Mac and iPhone apps generally extract RAR but do not create it. If you need to send files to someone else, ZIP is the safest choice and 7z the smallest.

Encryption: ZipCrypto, AES and file names

Compression shrinks; encryption hides. They are configured on one screen but are independent: a password does not make a file smaller, and compressing does not make it safe. Three points matter.

1) ZipCrypto and AES are different

The PKWARE APPNOTE (section 6.0.1) describes traditional ZIP encryption as "considered weak by today's standards" and recommends it only for low-security needs or compatibility with old ZIP software. Section 7.0 defines strong encryption with ciphers including AES [1]. Many tools just say "set password", so you may silently get the old method. For anything important, choose AES-256 explicitly. The cost is compatibility: some older tools cannot open AES ZIPs, so confirm the recipient can.

2) A password may not hide file names

A password-protected ZIP often still shows its file list. If names reveal content, information leaks. In 7-Zip, turning on file name (header) encryption for a 7z hides the list until the password is entered. If names are sensitive, use that option, or bundle everything into one neutrally named file before encrypting.

3) A weak password defeats any algorithm

AES-256 with "1234" is pointless. 7z derives its key through repeated SHA-256 hashing to slow brute force [2], but that cannot rescue a weak password. Use a long, hard-to-guess phrase and send it through a different channel than the archive.

Cross-platform pitfalls

Garbled file names (Korean, Japanese, Chinese and other non-English names)

The most common problem. The ZIP spec's default file name character set is IBM Code Page 437, and names are read as UTF-8 only when general-purpose bit 11 is set [1]. Archivers on Korean Windows that do not set the bit often store names in the system code page (CP949, Microsoft identifier 949) [5], and the same happens with other regional code pages. Opening that ZIP in a tool that assumes UTF-8 produces gibberish; the reverse also garbles names in old Windows tools that read UTF-8 as a local code page.

Fix it on both ends. As a receiver, use a tool that detects or lets you choose the encoding (for example CP949 versus UTF-8). As a sender, use a "Windows-compatible names" option if your tool has one, or use formats such as 7z or tar that store Unicode names. File contents are intact; only names are misread, so restoring names is enough. The Zipda section below shows this on screen.

Metadata macOS adds

A ZIP made on a Mac may show __MACOSX, .DS_Store and ._filename helper files when opened on Windows. They hold resource forks, extended attributes and folder view settings; they are hidden on macOS and look like clutter elsewhere. Deleting them does not damage your data. When sending to Windows or Linux users, use a tool or option that leaves them out. Another Mac-originated quirk is Korean letters shown split into separate jamo, caused by a different Unicode normalization form. That is a name representation issue, not corruption.

Already-compressed data does not shrink

JPG, MP4, existing ZIPs and images inside PDFs barely shrink. Bundling a photo folder is for sending one object, not for saving space; recompressing only costs time.

Large files and split archives

Mail or messenger limits sometimes force splitting. Naming differs: 7z and ZIP use numbered parts such as .7z.001 and .zip.001, or .z01, .z02 followed by .zip; RAR uses .part1.rar. The ZIP spec itself allows spanning multiple volumes or user-defined segment sizes [1].

1. Keep every part in one folder; a missing part blocks extraction.
2. Do not rename parts; tools find the set by naming pattern.
3. Open the first part (.001, .part1.rar, or the final .zip) and the rest follow.
4. Compare part sizes with the sender's. "Corrupted archive" usually means an interrupted download or a missing part.

Splitting is convenient, but losing one part loses everything. Often a different sharing route is better; see moving files between devices (Korean and English) for alternatives by size limit.

Which format should you choose?

The deciding factor is who receives the archive.

On Mac and iPhone: Zipda

The built-in tools on iPhone and Mac create and extract ZIPs, but RAR, 7z, encrypted archives and encoding problems are beyond them. Zipda, an iOS, iPadOS and macOS app I develop, targets those cases. This is the only section about it; everything above applies regardless of app. From the developer documentation and store listing:

• Opens, browses and previews ZIP, RAR, 7z and TAR archives and unzips ZIP and TAR in one step. Extracting RAR, 7z, ALZ and LZH is part of the optional Zipda Pro unlock. Creating ZIP is available, with AES-256 encryption for ZIP; creating 7z, password-protected and split archives is also part of Pro.
• No EGG support because of licensing and patent issues, and no RAR creation. LZH is extract-only.
• Opens password-protected ZIPs that use either the older ZipCrypto or AES (Pro).
• Detects file name encodings on the device and has a repair tool for garbled names. The developer docs note a limitation: very short Japanese names can be misread as Korean, so try another encoding if results look wrong.
• Opens files over 4 GB (ZIP64) and split sets without loading them into memory.
• Runs on the device with no account, no analytics and no advertising SDKs.

See the Zipda app page or the Zipda guide (Korean and English) for details. Whatever app you use, decide whether an archive from an unknown source is trustworthy before extracting it.

Troubleshooting

Sources

1. PKWARE, ZIP File Format Specification APPNOTE 6.3.9 (ZIP64 4.5.3, spanning 4.3.3, encryption 6.0.1 and 7.0, language encoding appendix D): APPNOTE-6.3.9.TXT
2. 7-Zip, 7z format page: 7-zip.org/7z.html
3. RARLAB, WinRAR version history: rarlab.com/rarnew.htm
4. Zstandard official site: facebook.github.io/zstd
5. Microsoft Learn, code page identifiers (949 Korean, 65001 UTF-8): code-page-identifiers

Not verified, so no figure is given: the maximum RAR file size and AES details, tar size limits, and per-version format support in the macOS and Windows built-in tools.

FAQ