CB7 (Comic Book 7z) file format

.cb7 · package (7z variant) · introduced 2008 by Comic reader community

What is a CB7 (Comic Book 7z) file?

CB7 is the 7z variant of the comic book archive convention. It typically produces the smallest comic files of all CB* variants and has the same per-page-image layout as CBZ.

Most readers reach this page after double-clicking a .cb7 file and finding their operating system unsure what to do with it. The good news: CB7 (Comic Book 7z) is a well-understood format with mature tooling on every major platform. It is supported in one click by mainstream archivers on Windows, macOS, and Linux.

How to extract a CB7 (Comic Book 7z) file

Opening a .cb7 file is straightforward on every modern operating system. The exact steps depend on which platform you are on:

On Windows

Locate the .cb7 file in File Explorer.
Right-click the file. If you have 7-Zip installed, choose 7-Zip → Extract Here. On Windows 11 the built-in extractor handles ZIP, 7z, RAR and several other formats directly through Extract All…
If prompted, pick a destination folder and click Extract.
The extracted files appear in a folder next to the original archive.

On macOS

Find the .cb7 file in Finder.
Install The Unarchiver from the Mac App Store, or Keka for both creating and extracting.
Right-click the file → Open With → The Unarchiver (or just double-click after Unarchiver is set as the default).
The extracted folder appears next to the archive.

On Linux

Use your file manager: right-click the archive → Extract Here (file-roller on GNOME, Ark on KDE).

On the command line, run one of:

7z x archive.cb7    # works for almost any format

The files appear in the current directory.

How to create a CB7 (Comic Book 7z) file

To pack files into a .cb7 archive, you typically need an archiver that supports writing this format. Not every tool can create every format — for example, only WinRAR can create real RAR files. The sidebar lists the software known to read and write CB7 (Comic Book 7z).

On the command line, the canonical create command is:

# Use 7-Zip, PeaZip, or the format's reference tool to create .cb7 files.

If you regularly create archives at scale, a dedicated archive automation suite can wrap this command in scheduled jobs, integrity checks, and offsite replication.

Strengths

Best compression for comics
Open format

Weaknesses and limitations

Less reader support than CBZ
Slower to open

Typical use cases

Compressed comic distribution where size matters

Technical details

CB7 (Comic Book 7z) uses the 7z / LZMA2 algorithm and is identified on disk by the magic byte sequence 37 7A BC AF 27 1C. The standard MIME type is application/x-cb7. The format is an open specification and is free for any use.

Frequently asked questions

Is CB7 (Comic Book 7z) safe to open?

Archive files are containers — they are only as safe as what they contain. A .cb7 from a trusted source is fine; one received from a stranger can hold malicious executables, scripts, or files engineered to exploit bugs in your archiver. Always keep your archiver updated, and never run unknown executables that come out of an archive. A safe workflow is to extract into a sandbox and scan the contents before opening anything.

What is the maximum file size?

Modern implementations support archives in the multi-terabyte range. The practical limit is your filesystem (FAT32 caps at 4 GB; ext4, NTFS, APFS, and exFAT all comfortably handle multi-TB files).

Can I password-protect a CB7 (Comic Book 7z)?

Some archivers can wrap CB7 (Comic Book 7z) files in an encrypted container, but the format itself does not always include built-in encryption. Check your archiver's documentation.

How does CB7 (Comic Book 7z) compare to other formats?

See our format comparison pages such as ZIP vs 7z, ZIP vs RAR, and tar.gz vs tar.xz for side-by-side feature tables.