ZIP Compressor & Extractor
ZIP has been the default archive format since 1989 because it is simple, universally supported, and stores each file independently so any one of them can be extracted without reading the rest. This page both creates and extracts archives, entirely in the browser.
How to use it
- Choose Create a ZIP or Extract a ZIP.
- Drop in the files to compress, or a single .zip to unpack.
- Download the archive, or the extracted files individually.
Why your archive barely got smaller
ZIP uses DEFLATE, which finds repeated byte sequences and replaces them with back-references. That works extremely well on text, where words and structural patterns recur constantly, and hardly at all on data that has already been compressed.
JPEG, PNG, MP3, MP4, WebP, and PDF are all compressed formats. Their bytes are close to incompressible by design, because the point of their own encoding was to remove exactly the redundancy DEFLATE looks for. Zipping a folder of photos typically saves one or two percent, and occasionally produces a slightly larger file once the archive metadata is counted.
Text-based content is the opposite case. Source code, CSV exports, JSON, logs, and XML routinely compress by 70 to 90 percent. If your archive did not shrink, the contents were already compressed, and the archive is serving as a container rather than a compressor.
ZIP encryption is not real protection
The original ZIP encryption scheme, often labelled ZipCrypto, is broken. A known-plaintext attack against it has existed for decades and recovers the contents in seconds given a small amount of known data, which is trivially available when the archive contains any file with a predictable header.
AES-256 ZIP encryption, supported by tools such as 7-Zip and WinZip, is genuinely strong, but it is an extension rather than part of the base specification, so support is inconsistent across platforms. Even with AES, filenames and directory structure remain visible in the central directory unless the archive is specially constructed to hide them.
This tool does not create encrypted archives. If you need confidentiality, encrypt with a purpose-built tool such as age or GnuPG and treat the ZIP purely as a container.
Extraction safety
A ZIP stores a path for every entry, and a maliciously crafted archive can store paths containing ../ sequences designed to write outside the intended directory when extracted. This is the Zip Slip vulnerability, and it has affected a long list of extraction libraries.
Extraction here writes nothing to your filesystem. Entries are decompressed into browser memory and offered as individual downloads, each handled by the browser own download machinery, which places files in your downloads folder using the filename only. There is no path to traverse.
Worth knowing separately: a zip bomb is a small archive that expands to an enormous size, and because extraction happens in memory here, a deliberately crafted bomb will exhaust the tab rather than your disk. Refreshing the page recovers.
At a glance
| Accepted input | Any files to compress, .zip to extract |
|---|---|
| Algorithm | DEFLATE |
| Encryption | Not supported, by design |
| Extraction target | Browser memory, then individual downloads |
Frequently asked questions
Why did zipping my photos save almost nothing?
JPEG and PNG are already compressed formats, and DEFLATE cannot remove redundancy that is already gone. The ZIP is acting as a container. Text-based files are where compression pays off.
Can I password-protect the archive?
Not here. Legacy ZIP encryption is cryptographically broken, and the strong AES variant has inconsistent cross-platform support. Use a dedicated encryption tool if you need confidentiality.
Is the folder structure preserved?
Paths are stored in the archive when compressing. On extraction, files are offered as individual downloads and land flat in your downloads folder, because the browser controls where downloads go.
Is there a size limit?
Everything is held in browser memory, so available RAM is the practical ceiling. Archives up to a few hundred megabytes are generally fine; multi-gigabyte archives are better handled by a desktop tool.
Read more
Working with documents: PDF, DOCX, and spreadsheets — Document formats encode intent as much as content, and conversions between them succeed or fail on whether that intent was recorded.