Files · Windows 10 and 11
Open 7Z files
7Z is the format of 7-Zip, popular for downloads and backups because it packs tighter than ZIP. Octoolo opens 7Z files, including locked ones whose names are hidden and big ones split into .7z.001, .7z.002 pieces.
How to open a 7Z file
- 1
Open the 7Z
In Files, press Choose an archive… under Extract, or drop it on that box. For a split file, open any part; all of them must be in the same folder.
- 2
Type the password, if asked
A 7Z with hidden names asks before it can show what is inside. Others show a lock on the files that need one, and ask when you extract.
- 3
Extract
In the Extract all box, the files go to a new folder beside the 7Z unless you press Change…; press Extract. For only some files, press Cancel, tick what you need and press Extract selected.
Solid archives
Most 7Z files are solid: many files compressed as one stream, which is a big part of why they are small. The catch is that a file in the middle can only be reached by unpacking the files before it. Octoolo does that for you, skips the blocks that hold nothing you picked, and says in the Extract box when picking files will take longer. Taking everything out costs nothing extra.
What opens, and what does not
- Methods: LZMA and LZMA2 (nearly every 7Z), PPMd, BZip2, Deflate, and the BCJ filters 7-Zip uses for programs.
- Passwords: AES-256, with or without hidden names.
- Split files:
name.7z.001,.002and on, read as one archive. The same works for ZIP and TAR files split that way. - Not yet: 7Z files made with the Zstandard, Brotli or LZ4 methods that some 7-Zip variants add, and self-extracting .exe archives.
Octoolo and 7-Zip
7-Zip, by Igor Pavlov, is the program the format comes from, and it is excellent at what it does. Octoolo's Files is for people who want archives handled in the same app as their PDFs, photos and videos, with a plainer window: choose an archive, see what is inside, press Extract. It also adds an Octoolo menu to File Explorer's right-click menu, with Extract here and Compress to ZIP. It has no command line and does not open disk images.
Besides 7Z it opens ZIP, RAR and TAR files (see open RAR files and extract TAR.GZ), and it makes 7Z files too: see make a 7Z file.
Octoolo or an online tool?
| Detail | Octoolo | A typical online tool |
|---|---|---|
| Your files | Stay on your computer | Usually uploaded to the site's server |
| Without internet | Works | Does not work |
| File size | No limit | Often capped on free use |
| Watermarks and ads | None | Common on free plans |
| Cost | $4.99 a month, all 17 apps | Free with limits, or a plan per site |
Questions, answered
Can Windows open 7Z files without an app?
Windows 11 can since a 2023 update, in File Explorer. Windows 10 cannot.
What if part of a split 7Z is missing?
Octoolo says which part to put in the same folder before it opens.
Can I turn a 7Z into a ZIP?
Yes: open it and press Convert to ZIP. See 7Z to ZIP.
Does it check the files are whole?
Yes. Every file is checked against its checksum as it comes out, and Test checks the whole archive without writing anything.
7Z extractor, and 16 more apps.
Download for Windows7 days free, then from $3.99 a month for all 17 apps. Windows 10 and 11.