How to create a 7Z file
- Drop files onto the drop zone above, or click Choose files. To include a whole folder, click Add a folder or drag the folder in; its structure is kept inside the archive.
- Type a name in Archive name. The default is
archive, which producesarchive.7z. - Click Create 7Z and wait while the files are compressed.
- Download the finished
.7zfile with its Download button.
Compression runs in your browser through libarchive compiled to WebAssembly. The files you add are never uploaded.
Why choose 7z?
The 7z format was introduced by 7-Zip and is built for compression ratio. Archives made here use LZMA, an algorithm that keeps a large dictionary of data it has already seen and encodes repeats very compactly. On text, source code, spreadsheets exported as CSV, and other repetitive data, a 7z is usually clearly smaller than a ZIP of the same files.
Not all content benefits. JPEG photos, MP4 videos, MP3 audio and most Office files are already compressed internally, so no archive format will shrink them much. For a folder of holiday photos the difference between 7z and ZIP is small, and ZIP has the advantage that every operating system opens it without extra software.
| 7Z (this tool) | ZIP | |
|---|---|---|
| Compression | LZMA, typically smaller | Deflate, faster |
| Opens without extra software | Recent Windows 11; elsewhere usually an extra app | Windows, macOS, Linux desktops |
| Keeps modification dates here | No | Yes |
| Password option here | No | Yes (AES-256) |
What to know about the result
Archives created by this tool do not store the original modification dates of your files. When someone extracts them, the files show 1970 or no date at all. This is a limitation of the browser build of libarchive. If dates matter, for example for backups or photo collections sorted by time, use ZIP or one of the TAR formats instead, which preserve them.
Empty folders are not stored, and if two files end up with the same path, the second is renamed with " (2)" appended. Everything is held in memory while the archive is built: totals above about 700 MB are slow, and more than 2 GB is refused.
The recipient can open the file with 7-Zip on Windows, 7z x archive.7z on Linux, a third-party extractor on macOS, or the Extract 7Z page in any browser.
Tips
- Need a password on the archive? Use Create ZIP with a password, or Password Protect Any File, both of which use AES-256.
- Already have a ZIP you want smaller? ZIP to 7Z repacks it with LZMA.
- For archives aimed at Linux servers, Create TAR.XZ gives similar compression and keeps dates.
Frequently asked questions
Can I set a compression level?
No. The only option is the archive name; LZMA compression is applied automatically.
Why do the extracted files show the date 1970?
Created 7Z archives do not record modification dates, so extractors fall back to the zero date. Choose ZIP or TAR if you need the original dates.
Can I add more files to the 7z later?
Not with this tool. Create a new archive containing all the files instead.