Open and Extract ZIP Files Online

How a ZIP archive is structured

A ZIP file format is specified by PKWARE APPNOTE.TXT. It is a set of independently compressed files plus an index called the central directory, stored at the end of the archive. The index records every entry's name, sizes, compression method and byte offset. Reading it is what lets this tool show you the full contents after reading only a few kilobytes.

Because entries are compressed separately, an individual file is decompressed without touching the rest of the archive. That is why saving one document out of a 500 MB ZIP takes as long as the document itself, not the whole archive.

How to extract a ZIP file online

1. Open the archive. Drop the .zip onto the box above, or click to browse. Only the archive's index is read at this point, so even a large file opens instantly.
2. Review the contents. Every entry is listed with its uncompressed size, packed size, compression method and modification date, so you can see what the archive holds before unpacking anything.
3. Preview text files. Click View on any text, CSV, JSON, XML, Markdown or source file under 2 MB to read it in place without saving it.
4. Save the files you want. Click Save on an individual entry to decompress just that file and download it. Nothing else is unpacked.

What you get out

• A complete file list — names, folder structure, uncompressed and packed sizes, compression method and modification date.
• Archive totals — file count, folder count, total unpacked size and the overall compression ratio.
• In-place previews — text, CSV, JSON, XML, HTML, Markdown, SRT and source files render in the page.
• Individual file downloads — decompressed one at a time, on demand.
• An exportable index — copy the list to the clipboard or download it as a tab-separated file for documentation or auditing.

Which archives this opens

Any standard ZIP archive opens, along with the many formats that are ZIP containers underneath: .jar, .apk, .epub, and the Office and OpenDocument formats .docx, .xlsx, .pptx and .odt. Opening a .docx this way is a quick route to the images stored inside it.

Stored and deflate entries — together, effectively every ZIP produced by Windows, macOS, 7-Zip and WinRAR — extract fully. Archives above 4 GB use the ZIP64 format and are reported rather than opened. .rar and .7z are different formats entirely and do not open here.

Why nothing is uploaded

The archive is read directly from your disk by the browser, in slices, and decompression uses the browser's own built-in DecompressionStream. No server participates at any point, so the file is never transmitted and no copy survives closing the tab.

Most "unzip online" services upload your archive, unpack it on their infrastructure and hand back a download link — which means your files sit on someone else's disk, often for hours. For an archive holding contracts, backups or client data, reading it locally is the safer default.

What this tool cannot open

Four cases are reported clearly rather than failing silently:

• Password-protected entries. Encrypted files are marked as locked. Decryption needs the password and a desktop tool such as 7-Zip.
• ZIP64 archives over 4 GB. These use extended offsets that this tool does not read.
• Unusual compression methods. Browsers decode deflate and stored data. bzip2, LZMA, Zstandard, XZ and PPMd entries are identified but not decompressed.
• Split and multi-part archives. Files like .z01 or .part1.rar must be rejoined before opening.

There is also no "extract all" button. Browsers restrict writing many files at once, so entries are saved individually and deliberately.

When opening a ZIP in the browser helps

• Checking a download before trusting it — read the file list of an archive from an unfamiliar source without unpacking it onto your disk.
• Grabbing one file from a large archive — pull a single invoice out of a monthly export instead of unpacking thousands of files.
• Working on a locked-down machine — extract files on a computer where installing 7-Zip is not permitted.
• Working on a phone or tablet — open an emailed archive without an unzip app.
• Auditing an archive's contents — export the file index as a record of what was delivered.

ZIP archives compared with self-extracting EXE files

A ZIP is a plain archive that any extractor opens. A self-extracting archive is a Windows executable with an archive appended to it, so it can unpack itself when run. Both often hold the same payload.

For a .exe installer, use the EXE extractor, which reads the executable's metadata and unpacks a ZIP payload when one is present. For a .docx whose text you want rather than its internal files, the PDF text extractor covers the PDF equivalent of that job.

For a guide to common reasons a ZIP refuses to open and how to fix each one, read why a ZIP file will not open.

ZIP format signatures and known edge cases

The ZIP format is defined by PKWare's APPNOTE.TXT (current version 6.3.10, 2022). Every entry starts with a local file header signature 0x504B0304 ("PK"). The central directory at the end of the file starts with 0x504B0102 ("PK
"), and the end-of-central-directory record starts with 0x504B0506 ("PK").

Three edge cases: (a) a self-extracting archive (SFX) prepends a Windows EXE stub before the ZIP data — the central directory is still at the end, so the extractor locates it correctly and lists all entries; (b) modification times are stored as MS-DOS date/time integers with 2-second precision and no timezone offset — timestamps may be off by your UTC offset versus the timezone of the machine that created the archive; (c) files compressed with Deflate64 (method code 9) rather than standard Deflate (method code 8) are listed correctly but cannot be decompressed here — browsers implement only Stored (0) and Deflate (8).

Frequently asked questions

Related extractors & guides

• EXE extractor — see what is inside a Windows executable before running it
• Icon extractor — pull the icon out of an EXE, DLL or ICO at every size
• MSI extractor — read a Windows Installer package and get at its CAB payload
• All archives & executables tools — and how to choose between them

Reviewed by Shah Abrar Ahmad & the EasyExtract Engineering Team • Specialist file parsing & security engineer • Verified: in our experience, our hands-on testing measured and verified private in-browser execution with zero file uploads • Last reviewed July 2026.