ZIP tools

See what is inside a ZIP file

Examine an archive without extracting anything. You get the folder tree, the sizes, the warnings and an integrity check — and nothing is written to your machine.

No extraction
No upload
No sign-up

This page downloads nothing. If you want to take files out, use Extract ZIP.

How it works

Three steps to knowing what you got

1
Choose the archive
We read only the table of contents, which sits at the end of the file. The files themselves are untouched, and an archive of several gigabytes is read as quickly as a small one.
2
Read what it says
Folder tree, file sizes, compression ratios and any warnings. If something is locked, you see which encryption method was used.
3
Check that it is intact
Press «Test the archive» and every file is read and compared with the checksum the archive states. You learn exactly which files fail, if any.

What you learn

Six things the archive tells you

The contents, not just the names

Press «Show» on a row and you see the file itself: images, text, JSON, CSV as a table, audio and video. Nothing is written to your machine.

A warning about ZIP bombs

If a file becomes more than 200 times larger when unpacked, we say so and show the ratio. A small archive can hide something enormous.

Paths that try to escape the folder

Names like «../../» try to write outside the folder you choose. We correct them, show the corrected name, and tell you it happened.

How it is locked

Locked files are marked with their encryption method — modern AES or the old, broken ZipCrypto. That says something about who made the archive.

A checksum for every file

Every file has a checksum in the archive. The test reads the file and compares, and finds damage that is invisible from the outside.

Old character sets read

Archives from the 1990s store file names in a character set that is not UTF-8. We read them as Nordic, so «h¢st.txt» is read as «høst.txt».

Questions and answers

What people ask

Is anything extracted when I use this page?

No. The tool on this page has no download buttons. If you choose «Test the archive», the files are read in memory to check them and discarded straight afterwards. Nothing is written to your disk.

Is it safe to preview a file I do not trust?

We built the preview assuming the content may be hostile. Nothing from the archive is interpreted as code: HTML and JavaScript are shown as plain text, and we show SVG as text too — an SVG file can contain scripts, so we do not render it. Images are shown with a file type we derive ourselves from the extension, not one that came with the archive. Program files are marked with a warning and never run. Nothing is shown until you press.

What is the checksum good for?

Every file in a ZIP archive has a CRC value that was calculated when the archive was made. If it does not match when we recalculate it, the file has been changed or damaged — for example because the download was interrupted. It is a readability check, not a security check.

What does «AES-256» or «ZipCrypto» mean in the list?

It is how the file is locked. AES is modern and gives real protection. ZipCrypto is from the 1990s and is considered broken — it can be cracked without guessing the password. If you see ZipCrypto on something meant to be secret, it should be repacked with AES.

Why do you warn about compression ratios?

An archive of a few kilobytes can unpack into many gigabytes and fill the disk or the memory. That is called a ZIP bomb. We compare the size inside the archive with the size after unpacking, and say so when the ratio is unreasonable — before you choose anything.

Can I see the contents of a single file?

Yes. Press «Show» on the row and the file is extracted in the browser and shown below the list — images, plain text, JSON, CSV as a table, audio and video. You also get the size, compression method, date and checksum. The file is not written to your machine, and you can close the preview by opening another archive. PDF is not shown: a PDF can contain scripts, and we will not open it in a window on the page until we can do it safely.

Is this a virus scan?

No, and it will not become one. We say whether the archive can be read and whether the files are intact. We say nothing about what the content does. Use an antivirus program for that.

Other tools and pages

Extract ZIP Take the files out once you have seen what is there. Open ZIP file Open the archive and take out what you want, in one operation. Create ZIP file Collect files and folders into one archive, with no upload.