What is a .zip file?
ZIP Archive · Archive · PKWARE · 1989
ZIP is the most common way to bundle and compress files. Built into Windows, macOS and Linux, it packs a folder into one smaller file for easy sending and storage, and it is also the basis of DOCX, EPUB and many other formats.
What is a .zip file used for?
A ZIP archive stores many files and folders in one compressed container. Every major operating system can create and open ZIPs without extra software.
Its compression is decent and its compatibility is unbeatable, which is why it quietly underpins countless other formats. DOCX, XLSX, EPUB, JAR and APK are all ZIP files inside.
For higher compression, formats like 7z and RAR do better, but ZIP wins on universal support.
What opens a .zip file?
The .zip format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- File Explorer
- 7-Zip
- WinRAR
macOS
- Archive Utility
- The Unarchiver
Linux
- Archive Manager
- unzip
Web
- Not natively; download and extract
Open a .zip file step by step
- Confirm the file really is a .zip. Drop it into the WhatFileType identifier, which reads its signature in your browser without uploading anything.
- On Windows, open it with File Explorer or 7-Zip.
- On Mac, use Archive Utility or The Unarchiver.
- On Linux, try Archive Manager or unzip.
- Still stuck? Convert the .zip to 7Z, which opens more widely.
Why can't I open my .zip file?
Almost always because no installed app understands ZIP. Install one of the apps above, or convert the file to a format your existing software already reads. If double-clicking opens the wrong program instead of nothing at all, the file association is set to the wrong app rather than the file being broken.
The other possibility is that the file is not really a .zip at all. Drop it into the file identifier to check it by its bytes instead of its name. Nothing is uploaded.
How to convert a .zip file
You can convert a .zip file to 7Z, TAR.
7-Zip and the built-in Windows and macOS tools all read ZIP. Re-archiving to 7z typically shrinks a text-heavy archive by a third, at the cost of needing 7-Zip to open it.
What is the .zip file signature (magic bytes)?
A .zip file starts with the hex bytes 50 4B 03 04, which read as PK.. in ASCII. Programs identify ZIP by those bytes, not by the filename, so a renamed file still gives itself away.
These are the documented signatures for ZIP. For a full breakdown, see the ZIP file signature page.
| Hex signature | Offset | ASCII | Note |
|---|---|---|---|
| 50 4B 03 04 | 0 | PK.. | local file header |
| 50 4B 05 06 | 0 | PK.. | empty archive |
| 50 4B 07 08 | 0 | PK.. | spanned archive |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .zip file?
ZIP is the most common way to bundle and compress files. Built into Windows, macOS and Linux, it packs a folder into one smaller file for easy sending and storage, and it is also the basis of DOCX, EPUB and many other formats.
How do I unzip a file?
On Windows, right-click and choose Extract All. On Mac, double-click it. On Linux, use the Archive Manager or the unzip command.
Are ZIP files safe?
The ZIP itself is harmless. The danger is what it contains, so scan unexpected archives before opening the files inside.