`.zip` File Extension

Learn what a .zip archive is, how to open it safely, how Poly supports ZIP files, and when another archive format may fit better.

File extension details for `.zip`

Storage Only

File type	ZIP archive
MIME type	`application/zip`
Encoding	Binary archive with per-member storage or compression
Operating systems	Windows, macOS, Linux, iOS, Android
Opens with	Windows File Explorer, macOS Finder, 7-Zip, Archive Utility
Poly support	Yes. Poly stores, syncs, shares, versions, and downloads `.zip` archives.
Indexed by Poly	Partial. Poly indexes the archive's filename and ordinary file properties, not its members.
Preview in Poly	No. Download the archive to browse or extract it with a trusted utility.
Poly agent	No. The Poly agent cannot read files while they remain packed inside the archive.

What kind of file is a `.zip`?

A .zip file is a binary archive that bundles files and folders into one container. Its registered MIME type is application/zip. Each member can be compressed independently, stored without compression, encrypted, or digitally signed. DEFLATE is the compression method most ZIP tools use by default.¹

Most non-empty ZIP archives start with 50 4B 03 04, the local-file-header signature. An empty archive may start with 50 4B 05 06, the end-of-central-directory signature.¹ Those bytes are a useful clue, but a safe tool must validate the archive records and directory rather than trust the filename or first four bytes alone.

Renaming backup.7z, backup.tar, or another file to backup.zip does not convert it. Extract and repack the contents with an archive utility when you need a real ZIP file.

How do I open a `.zip` on my computer?

On Windows, File Explorer can open compressed folders and extract all or selected files.²
On macOS, double-click the archive in Finder to expand it. Finder's Compress command creates ZIP files.³
On Linux, desktop archive managers and command-line tools such as unzip are widely available.
On iPhone and iPad, Apple's Files app can create and extract ZIP archives.⁴
On Android, Files by Google can extract .zip files.⁵

For encrypted archives, split sets, ZIP64, or less common compression methods, use a current archive utility such as 7-Zip. Support for one ZIP feature does not guarantee support for every method or encryption profile.

Inspect archives from unfamiliar sources before opening extracted files. Extract into a new empty folder, reject paths that escape it, and watch for unexpectedly large expanded sizes or nested archives. IANA specifically warns that extraction can overwrite existing files.⁶

Poly support for `.zip`

Poly stores, syncs, shares, versions, and finds .zip archives by filename and ordinary file properties. It does not currently extract them, list member names, generate a ZIP preview, index packed content, or give the packed files to the Poly agent.

Download and extract the archive with a trusted utility when you need its contents. Add the extracted files to Poly separately so each supported format can receive its own preview, metadata, search, and agent features.

History of `.zip`

PKWARE first published the ZIP specification in 1989 and continues to maintain the format through its APPNOTE specification.¹ The initials PK in ZIP record signatures point to PKWARE.

The application/zip registration dates to July 1993 and defines ZIP as binary data with no required or optional media-type parameters.⁶ ZIP64 later extended classic 32-bit size fields and 16-bit entry counts, allowing archives beyond 4 GiB and 65,535 members.¹

Working with `.zip` and alternatives

ZIP is a strong default for exchanging several files because major desktop operating systems open it without extra software. Already-compressed JPEG, MP4, and many PDF files may shrink very little inside a ZIP.²

Format	Best fit	Tradeoff
`.zip`	Broad cross-platform sharing and selective extraction	Unix metadata and advanced features vary by tool
TAR + Gzip	Unix-style directory trees and distribution	Uses separate archive and compression layers
`.7z`	More compression choices and optional solid compression	Less universal built-in support

Repacking an archive can lose permissions, links, timestamps, comments, or encryption settings. Keep the original when exact preservation or provenance matters.

PKWARE, Inc. .ZIP File Format Specification (APPNOTE). Defines record signatures, compression methods, CRC-32, encryption, central directories, and ZIP64. ↩ ↩² ↩³ ↩⁴
Microsoft Support. Zip and Unzip Files. Documents Windows ZIP creation and extraction and notes that already-compressed JPEGs usually shrink little. ↩ ↩²
Apple Support. Zip and Unzip Files and Folders on Mac. Documents Finder's Compress command and double-click extraction. ↩
Apple Support. Create or Open ZIP Files on Your iPhone or iPad. Documents ZIP creation and extraction in the Files app. ↩
Google. Unzip Your Files. Documents .zip extraction with Files by Google. ↩
Internet Assigned Numbers Authority. application/zip Media Type Registration. Records the media type, 1993 registration date, binary encoding, and extraction warning. ↩ ↩²

.zip File Extension

File extension details for .zip

What kind of file is a .zip?

How do I open a .zip on my computer?

Poly support for .zip

History of .zip

Working with .zip and alternatives

Footnotes