Archive File Extensions: ZIP, RAR, 7z, TAR.GZ and the Names That Lie

The letters after the last dot are a suggestion from whoever saved the file. Windows, macOS and phones all use that suggestion to pick an icon. They will happily show a ZIP icon on a RAR, or hide the .exe on a file that looks like a PDF. This page is a field guide to the extensions UnpackNest and desktop tools actually key off, and to the disguises that still fool people.

Updated 2026-10-22 · Written and tested by the UnpackNest editorial team (TECCONET)

The extensions you will actually meet

Two names for one format are normal. A .tgz and a .tar.gz that hold the same project are the same kind of file. A .zipx is a ZIP that may use methods the basic unzipper does not know. If the ZIP tool says the method is unsupported, 7-Zip on a computer is the next stop, not a rename to .zip.

Double extensions

statement.pdf.zip means "a ZIP, and the sender hopes the thing inside is a PDF". You open the ZIP. You do not rename it to .pdf. After extraction you should see a real .pdf whose size is in the same range as a document, not a few kilobytes of HTML.

photo.jpg.rar is a RAR. backup.tar.gz.zip is a ZIP that contains a tarball. Read from the right: the final extension is the outer container. Each layer comes off with the matching tool, which is the nested-archive workflow.

The dangerous cousin is invoice.pdf.exe or invoice.pdf.js. The final extension is the program. The .pdf in the middle is decoration. If your computer hides known extensions, the file can look like invoice.pdf in the folder and still be an executable. Turn the real name on before you open mail downloads.

Make Windows show the real name

1. Open File Explorer.
2. On Windows 11, choose View, then Show, then File name extensions.
3. On Windows 10, choose View in the ribbon and tick File name extensions.

Do this once per user account. It is the single most useful setting for anyone who receives archives. macOS Finder shows extensions unless a file has "Hide extension" ticked in Get Info. iOS Files shows the extension in the name more often than Windows does, but the icon can still be generic.

When the name and the bytes disagree

Tools that read signatures will disagree with a lying name, and that disagreement is good news.

1. Try the tool that matches the extension.
2. If it says "not a ZIP" or "not a RAR", try the other UnpackNest tools before you re-download. A renamed file opens in the tool that matches the signature.
3. If every tool refuses it and the file is small, open it with a text editor. A download that failed often starts with <!DOCTYPE html or with the words "access denied". There is no archive inside.
4. If the file is large and every signature fails, it may be truncated so badly that the header is gone, or it may be encrypted at the file level (GPG, OpenSSL) rather than as a ZIP password. The TAR tool calls out OpenSSL and GPG streams. Other formats need the program that created them.

Renaming a broken file from .zip to .rar does not repair it. Renaming is only legitimate when you already know the signature, for example a browser that saved download with no extension and the sender told you it was a ZIP. Add the extension, do not cycle through them at random.

Volume suffixes that are part of the name

.part1.rar uses an extra dot. The extension is still .rar, and the .part1 says which volume. .r00 is an extension by itself on old RAR sets. .z01 belongs to split ZIP. .7z.001 is two suffixes: 7z plus a volume index. None of these should be stripped "to tidy the folder". The multi-part guide and the split-7z guide depend on those names staying intact.

A file named .zip.part is often a browser's unfinished download (Firefox and some download managers). It is not a split ZIP. Wait for the download to finish, or restart it. Opening a .part file fails because the bytes are an incomplete copy of whatever the real file was.

Compression suffixes on a single document

People gzip a single CSV and send data.csv.gz. After a successful gzip extract you should have data.csv, not a folder. If the tool lists many files, you were sent a tarball and the name was shortened to .gz by a phone. Open it as TAR. The GZ guide separates those two cases with the exact commands on a desktop.

xz and bz2 work the same way for a single file (report.xml.xz) and as a wrap on TAR (report.tar.xz). The extension in the middle, when it is present, tells you there is still a TAR to undo.

Unicode, Arabic, and right-to-left names

Archive members can be named in Arabic or any other language. ZIP's old path encoding sometimes scrambles those names into Latin-1 noise. 7z and PAX TAR keep Unicode more reliably. If you see ملف instead of an Arabic word, the file is probably fine and the name was decoded with the wrong code page. Extract with 7-Zip and set the code page, or ask the sender to re-pack with a current ZIP tool that sets the UTF-8 flag. Do not "fix" the name by guessing the extension from the mojibake.

Right-to-left file names can display the extension on the left of the string in some apps. Select the file and look at the properties panel, which prints the name in a direction you can read character by character. The last extension is a property of the string, not of where the icon drew it.

Frequently asked questions

My phone says the type is "document" and shows no extension

Use the share sheet's Save to Files, then open the details pane. If there is still no extension, look at the size and at who sent it, and try the ZIP tool first only if the sender said ZIP. A missing extension plus an unknown sender is a reason to stop, not a reason to try every app.

Is a .cab or .rar the same family?

No. CAB is a Microsoft cabinet file. RAR is not. UnpackNest does not open CAB. 7-Zip on Windows does. Bring a CAB here only after someone has repacked it as ZIP, and only if you trust that someone.

The file is .zip but the ZIP tool mentions ZIP64

ZIP64 is still a ZIP. It is the extension of the format past the old 4 GB limits. The ZIP tool supports it. You do not rename ZIP64 files. There is no .zip64 extension in normal use.

Can I trust the MIME type the browser shows?

It is another suggestion, often taken from the extension or from the server's header. A server can label a RAR as application/zip. The signature the tool reports is the check that matters. If the tool lists real entries, you have the format it claims, whatever the download bubble said.

Related guides

• 7z vs ZIP vs RAR: Differences, Strengths and When to Use Each
• How to Open GZ Files: .gz, .tar.gz and .tgz Explained
• What Is a RAR File? A Practical Guide to Opening and Extracting It
• How to Open .tar.gz and .tgz Files on Windows, Mac and Your Phone