What is the B6Z file format?
A .b6z file is a compressed archive created by B6Zip, a macOS compression utility. Like other archives, it bundles one or more files and folders into a single container so they take up less space and are easier to share. By default the format compresses data with LZMA2, and it can also use LZMA, Deflate, BZip2 or PPMD. Archives can be locked with AES-256 encryption and a password.
Internally, B6Z borrows the layout of .zip. Each stored file begins with a local header whose signature is the bytes 42 36 03 04 ("B6"), and an index called the central directory sits at the end of the file starting with 42 36 01 02. The B6Zip tool could also read .zip, .tar and .rar archives. The app is no longer maintained, which is why loose .b6z files sometimes turn up without the software that made them.
Security & safety
RISK: MEDIUMA .b6z file is a data archive, not a program, so it does not run on its own. The real risk is in what it contains: extracted executables or scripts can carry malware, so scan unpacked files before running them. Encrypted .b6z archives require the correct password to open. Because B6Zip is discontinued, prefer a well-maintained extractor like 7-Zip and verify the source of any archive you did not create.
Format details
in a nutshellPrograms that open B6Z files
Windows2 apps
macOS3 apps
Keka
Free Drag the .b6z file onto Keka to extract its contents; Keka handles LZMA2-based archives and a wide range of other formats.
p7zip (7-Zip CLI)
Open-source Run 7z x archive.b6z in Terminal to list and extract members from the ZIP-style container. 
Linux1 app
p7zip (7-Zip CLI)
Open-source Install p7zip and run 7z x archive.b6z to extract the archive from the command line. Technical details
deep spec| Encoding | Binary |
| Byte order | Little-endian |
| Container | ZIP-style container with local file headers plus an end-of-file central directory |
| Compression | LZMA2 by default; also LZMA, Deflate, BZip2 and PPMD |
| Encryption | AES-256 with password protection (optional) |
| Typical size | Varies with payload; format specifies a very large addressable ceiling |
| Max File Size | Documented ceiling of roughly 900,000 PB |
| Structure | Sequence of compressed member entries each preceded by a local header (42 36 03 04), followed by a central directory (42 36 01 02) at the end that indexes the members. |
| Integrity | Integrity checks and error recovery for detecting and repairing corruption |
| Platforms | macOS |
| Notes | Marketed as a high-ratio solid archive format with metadata compression, file spanning and the ability to read ZIP, TAR and RAR archives. Created by the B6Zip application, which is now discontinued. |
| Released | 2010s |
| Open standard | Yes · royalty-free |
| Specification | b6zip.com |
B6Z conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about B6Z files.
Frequently asked questions
How do I open a .b6z file?
What program created .b6z files?
Is a .b6z file safe?
Why won't my .b6z file open?
Can I convert a .b6z file to .zip?
.zip. There is no single-click B6Z-to-ZIP converter.
