Question 1

What does this tool do?

Accepted Answer

It extracts files from ZIP archives in your browser using a pure-JavaScript ZIP parser. Supports both STORE (no compression) and DEFLATE entries — DEFLATE decompression uses the browser's native DecompressionStream API, available in all modern browsers (Chrome 80+, Firefox 113+, Safari 16.4+, Edge 80+). You can browse the file tree, search by name, filter by extension, preview text files, download individual files, or re-zip everything for download.

Question 2

How does it handle DEFLATE-compressed entries?

Accepted Answer

ZIP archives commonly store entries with the DEFLATE algorithm (compression method 8). When we encounter such an entry, we pipe its raw compressed bytes through a DecompressionStream('deflate-raw') instance, which handles the inflate algorithm in native code. This is much faster than a pure-JS DEFLATE decoder and ships at zero bundle cost. For STORE entries (method 0), we just return the bytes verbatim.

Question 3

Are password-protected ZIPs supported?

Accepted Answer

No. Decrypting ZipCrypto or AES-encrypted ZIPs requires either an external WASM library (~3MB) or significant custom crypto code. We document this as an intentionally-omitted feature to keep the bundle size under 50KB gzipped. If your ZIP is password-protected, you'll see an error mentioning 'unsupported compression method 99' or an encryption flag.

Question 4

Can I preview file contents?

Accepted Answer

Yes. Click the eye icon next to any file to preview its first 8KB. Text files (UTF-8, ASCII) are shown as decoded text. Binary files are shown as a hex dump with ASCII gutter. The preview is read-only — extraction gives you the raw bytes.

Question 5

How do I download all files at once?

Accepted Answer

Click 'Download all as ZIP' to re-zip every file from the archive into a new STORE-method ZIP. This is useful when the original archive uses DEFLATE and you want a portable uncompressed version, or when you want to filter to a subset of files and download just those.

Question 6

What extra features does this tool have compared to others?

Accepted Answer

10 extras: (1) Drag-drop input. (2) File tree view — group files by directory. (3) Search files by name (case-insensitive). (4) Filter by file extension (.txt, .png, .csv, etc.). (5) Preview text files inline (UTF-8 decode) with hex fallback for binary. (6) Stats — file count, total uncompressed size, compressed size, compression ratio. (7) Download individual files. (8) Download all as ZIP (re-zip STORE method). (9) History of recently extracted archives (localStorage — last 10). (10) Shareable URL with filter + search preset.

Question 7

Is my ZIP file uploaded anywhere?

Accepted Answer

No. All ZIP parsing and DEFLATE decompression runs in your browser using pure JavaScript + the native DecompressionStream API. File contents never leave your device. Only archive summaries (filename + entry count) are saved to local history.

Question 8

What's the maximum ZIP size?

Accepted Answer

There's no hard limit, but very large archives (>1GB) will use lots of memory because we parse the whole central directory at once and may decompress multiple entries in memory simultaneously. The browser's per-tab memory cap (~2-4GB) is the practical limit. ZIP64 archives (>4GB or with files >4GB) are partially supported — the local file headers parse correctly, but 64-bit size fields in the central directory are not yet implemented.

ZIP Extractor

How to use