7-Zip BZip3

Windows x64 fork of 7-Zip 26.01 with bzip3 integrated as a first-class archive format.

What changed

• Adds native .bz3, .bzip3, and .tbz3 support to 7z.dll, 7z.exe, 7zG.exe, and 7zFM.exe.
• Makes bzip3 the default GUI compression choice for single-file compression.
• Adds Explorer quick actions for stock .7z archives and for BZip3 archives.
• Uses .bz3 for single-file quick compression and .tar.bz3 for folders or multi-select, while keeping the normal 7z/zip/xz/bzip2 choices available.
• Ships a GitHub Actions release pipeline that builds a portable package and an MSI installer with shell integration.

Build

Local x64 build

cmd /c '"C:\Program Files (x86)\Microsoft Visual Studio\2022\BuildTools\VC\Auxiliary\Build\vcvars64.bat" && nmake'

Run that from CPP\7zip.

Package portable release

.\scripts\Package-Release.ps1 -Version 26.0.1

Smoke test packaged binaries

.\scripts\Smoke-Test.ps1

GitHub Actions release

Push a tag such as v26.0.1. The workflow in .github/workflows/release.yml builds:

• 7zip-bzip3-x64-<version>-portable.zip
• 7zip-bzip3-x64-<version>.msi
• SHA256SUMS.txt

Notes

• BZip3 is a single-stream format. For folders or multi-file shell quick actions, this fork creates a .tar.bz3 archive.
• The installer registers the standard 7-Zip shell extension hooks so Windows Explorer gets pack and unpack context-menu entries.
• The release package includes both the 64-bit shell extension and the 32-bit companion DLL used by 32-bit shell hosts on x64 Windows.

Licensing

• 7-Zip source remains under the licenses described in DOC\License.txt.
• The integrated BZip3 code is LGPL v3; see BZip3-LICENSE.txt.