ZIP file format

.zip · archive+compression · introduced 1989 by Phil Katz (PKWARE)

What is a ZIP file?

ZIP is the most widely supported archive format on Earth. Created by Phil Katz in 1989 as an open replacement for ARC, it bundles many files into a single .zip container and compresses each one individually using DEFLATE. Every modern operating system can open ZIP files without third-party software, which is why it is the default choice for sharing folders by email or download.

Most readers reach this page after double-clicking a .zip file and finding their operating system unsure what to do with it. The good news: ZIP is a well-understood format with mature tooling on every major platform. It is supported in one click by mainstream archivers on Windows, macOS, and Linux.

How to extract a ZIP file

Opening a .zip file is straightforward on every modern operating system. The exact steps depend on which platform you are on:

On Windows

Locate the .zip file in File Explorer.
Right-click the file. If you have 7-Zip installed, choose 7-Zip → Extract Here. On Windows 11 the built-in extractor handles ZIP, 7z, RAR and several other formats directly through Extract All…
If prompted, pick a destination folder and click Extract.
The extracted files appear in a folder next to the original archive.

On macOS

Find the .zip file in Finder.
Double-click the file. macOS Archive Utility opens automatically and extracts to the same folder.
The extracted folder appears next to the archive.

On Linux

Use your file manager: right-click the archive → Extract Here (file-roller on GNOME, Ark on KDE).
On the command line, run one of:
```
unzip archive.zip
```
The files appear in the current directory.

How to create a ZIP file

To pack files into a .zip archive, you typically need an archiver that supports writing this format. Not every tool can create every format — for example, only WinRAR can create real RAR files. The sidebar lists the software known to read and write ZIP.

On the command line, the canonical create command is:

zip -r archive.zip folder/

If you regularly create archives at scale, a dedicated archive automation suite can wrap this command in scheduled jobs, integrity checks, and offsite replication.

Strengths

Universal support
Random access to any file inside
Streamable
Mature tooling

Weaknesses and limitations

Compresses each file independently (no solid archive)
Weaker compression than 7z/xz
Legacy ZipCrypto encryption is broken — use AES-256

Typical use cases

Email attachments
Software distribution
Document bundles
Office (.docx, .xlsx) container
Java JAR / Android APK container

Technical details

ZIP uses the DEFLATE (also store, BZIP2, LZMA) algorithm and is identified on disk by the magic byte sequence 50 4B 03 04. The standard MIME type is application/zip. The format is an open specification and is free for any use.

Frequently asked questions

Is ZIP safe to open?

Archive files are containers — they are only as safe as what they contain. A .zip from a trusted source is fine; one received from a stranger can hold malicious executables, scripts, or files engineered to exploit bugs in your archiver. Always keep your archiver updated, and never run unknown executables that come out of an archive. A safe workflow is to extract into a sandbox and scan the contents before opening anything.

What is the maximum file size?

Modern ZIP-based formats use the ZIP64 extension to support archives larger than 4 GB and individual files larger than 4 GB, up to 16 EB in theory. Older tooling that does not understand ZIP64 will report a corruption error on such files.

Can I password-protect a ZIP?

Yes. ZIP supports password protection with AES-256 encryption in modern archivers like 7-Zip, WinRAR, and PeaZip. Avoid the legacy ZipCrypto algorithm — it has been broken for years.

How does ZIP compare to other formats?

See our format comparison pages such as ZIP vs 7z, ZIP vs RAR, and tar.gz vs tar.xz for side-by-side feature tables.