About Online ZIP Viewer

What this is

Online ZIP Viewer opens ZIP archives in your web browser so you can see what is inside them, preview individual files, and download only the parts you actually want. There is nothing to install, nothing to sign up for, and no limit on how much you use it.

The whole thing is a static website plus some JavaScript. When you open an archive, that JavaScript reads it directly in your browser using the same sandbox that keeps every other website from touching your computer. Your file is not sent anywhere.

Why we built it

Search for a way to open a ZIP file online and you will find plenty of options. Look at how they work, though, and a pattern emerges: almost all of them ask you to upload the archive. Your file travels to a server owned by someone you have never met, gets unpacked there, and sits in temporary storage for however long that operator decides.

For a photo of a cat, fine. For an export of your own personal data, a client's confidential assets, or a folder of tax paperwork, that is a genuinely bad trade for the convenience of not installing software.

Browsers have been able to do this work locally for years. The technology to read a ZIP file in a tab has existed for well over a decade. Almost nobody built the tool that way, because uploading is easier to engineer and creates a business with metered tiers to sell. We thought the better version should exist.

How it works

When you drop in an archive, the browser hands us the bytes and we parse the ZIP structure in a background thread — a Web Worker — so the page stays responsive even on very large files. We read the archive's central directory to get an accurate list of every entry with its real size, date and compression details, then build the folder tree you see.

Nothing is decompressed until you ask for it. Click a file and only that file is extracted, in memory, for as long as you are looking at it. Close the archive and it is gone.

The one piece of server code we run is a relay for the open-from-URL feature. Browsers refuse to read a file from another domain unless that domain opts in, and most file hosts do not. So when a direct fetch is refused, we stream the bytes through our own endpoint to complete the download. It handles only public URLs you typed yourself, it writes nothing to disk, and it keeps nothing.

What we believe

A tool should do one job properly. This one views ZIP files. It does not want your email address, it will not follow you around the internet, and it does not have a Pro tier.

Being honest about limits is part of that. Password-protected archives cannot be opened here, because the decryption formats involved are not supported by the library we use — so we tell you that clearly instead of failing with a vague error. Very large archives are bounded by your device's memory, not by a rule we invented. And the URL relay is a real server touching real bytes, so we describe it rather than claiming a purity we do not have.