Extract a 7z online
A .7z file is the one the operating system usually refuses. Windows Explorer and macOS Archive Utility understand ZIP and a few others, but 7z — with its LZMA/LZMA2 compression, solid archives, and strong AES-256 encryption — needs a 7-Zip-compatible decoder, so the usual answer is "install 7-Zip." ZipTool skips that step: it runs a WebAssembly build of 7-Zip inside your browser, so you drop the .7z on the page and it is decoded locally, with nothing uploaded and nothing installed.
You open the page, add the .7z (drag it, pick it, or paste a URL), and the archive is parsed in your tab. The file tree renders locally, you browse and preview the contents, and when you are ready you extract — writing the original files to a folder you choose on Chrome and Edge, or downloading them as a bundle on Firefox and Safari. The decode-and-extract loop runs entirely client-side.
How to extract a 7z in your browser
The first time you open a 7z, the browser fetches the WebAssembly 7-Zip module (a one-time download, cached afterward); after that, decoding any 7z in that browser is local.
- Add the .7z. Drag it onto the page, pick it from disk, or paste a direct URL. The bytes are read locally — no upload.
- Browse the tree. The 7z contents render as a folder tree. Expand folders, search across the whole archive by name, and click any entry to preview it first.
- Extract. Use the extract-all control in the file-tree toolbar. On Chrome and Edge, pick a destination folder and the original files are written there with their structure intact; on Firefox and Safari, the contents download as a clean zip.
- Or download single files. Preview an entry and save just that file when that is all you need.
Why 7z needs a special decoder
7z is an open format (the 7-Zip project, by Igor Pavlov). Its strength is compression ratio: LZMA and LZMA2 typically produce smaller archives than ZIP's Deflate, especially across many small files, because 7z can treat the whole archive as one solid stream. The trade-off is exactly what makes a browser decoder necessary — the built-in OS tools do not speak LZMA, so recipients need a 7-Zip-compatible extractor, and extraction is more memory- and CPU-hungry than ZIP.
ZipTool uses a WebAssembly build of 7-Zip to do that decoding in your tab. That is also why it can handle password-protected 7z archives: 7z's AES-256 encryption is part of the format the decoder understands. For the format background, see what is a 7z file; to browse rather than extract, see the 7z page and the 7z viewer; for step-by-step opening, see how to open a 7z file.
Extraction versus previewing a 7z
Previewing means looking inside the 7z without writing anything — ZipTool renders the tree and shows you files one at a time, in place. Extracting decompresses the entries and writes them out as real files and folders. Because 7z archives are often large and slow to fully unpack, preview-first is especially valuable here: glance at the tree, check sizes, and extract only what you actually want rather than decompressing the whole thing blindly.
Inside a 7z you can preview the same content types as anywhere else — source code and config with syntax highlighting, images, PDFs, audio, and video. Nested archives (a zip or another 7z stored inside) open as their own archive without leaving the page.
Privacy: 7z contents never leave your device
People reach for 7z precisely because the contents matter — large backups, software distributions, sensitive bundles. The upload-based 7z extractors ask you to send that to their server, decrypt it there, and trust them with the result. A client-side extractor removes that trust requirement. Your .7z is decoded in your tab and written to a folder you chose; no complete, decrypted copy ever exists on another machine.
Verify it yourself: open a 7z, then watch DevTools' Network tab — you see the page load and the one-time WASM fetch, but no upload of your archive. Disconnect from the internet and confirm browsing, previewing, and extracting keep working. For the broader argument, see why client-side is safer than uploading.
Honest limits
A browser-based 7z extractor is capable, but it has real boundaries worth knowing.
- Large 7z archives take time and memory. LZMA decoding is heavier than Deflate, and a solid archive must be processed as one stream. Very large 7z files can be slow or, at the extreme, exhaust a browser tab's memory. Open 7z files from sources you trust, and be cautious with archives that claim enormous uncompressed sizes.
- Extract-to-folder needs Chrome or Edge. Writing a real directory tree uses the File System Access API, which Firefox and Safari lack. On those browsers you still get every file, bundled as a downloadable zip that preserves the folder structure.
- You cannot create a 7z. This build of the decoder is read-only for the formats you can output; ZipTool can create and convert to ZIP, TAR, and TAR.GZ, but not to 7z. To produce a
.7z, use the desktop 7-Zip program. See create a zip online for the supported write side. - Password-protected 7z needs the password. ZipTool can decrypt AES-encrypted 7z archives when you supply the password; it cannot bypass encryption you do not have the key for. No honest tool can.
Frequently asked questions
How do I extract a 7z file online without installing 7-Zip?
Open the page and drop your .7z onto it. ZipTool decodes the archive in your browser using a WebAssembly build of 7-Zip — no install, no account, no upload. Browse the file tree to confirm the contents, then use the extract-all control to write the files to a folder (Chrome/Edge) or download them as a zip (Firefox/Safari).
Why will Windows or macOS not open my .7z file?
The built-in tools (Windows Explorer, macOS Archive Utility) do not understand 7z's LZMA/LZMA2 compression, so they refuse the file rather than risk a wrong extraction. You need a 7-Zip-compatible decoder. ZipTool provides one in the browser, or you can install the desktop 7-Zip program.
Do you upload my 7z file?
No. The 7z is decoded entirely in your browser using a WebAssembly 7-Zip module; your file contents are never transmitted to a server, never stored, and never handed to a third party. The only network traffic is the page itself and a one-time fetch of the decoder module. You can confirm there is no upload in DevTools, and by disconnecting from the internet after the page loads — extracting keeps working.
Can it extract a password-protected 7z?
Yes, when you have the password. 7z uses strong AES-256 encryption, and ZipTool's decoder can decrypt it once you enter the password. It cannot open an encrypted 7z without the key — no honest tool can bypass encryption. By contrast, ZipTool cannot decrypt password-protected RAR files.
Can I open a 7z on my phone?
Yes. ZipTool runs in any modern mobile browser with no install. Open the page, pick or drop the .7z, browse it, and extract. On mobile browsers without the directory-writing API, the contents download as a zip rather than a native folder. Be aware that very large 7z files can be slow or memory-heavy on a phone.
Is extracting a 7z online free?
Yes. Browsing, searching, previewing, and extracting a 7z is completely free, with no account and no install. The decoder runs locally; there is no per-file or per-archive paywall.