WBZ & WLZ (File Formats)

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WBZ and WLZ are alternative file formats. They use bzip2 and LZMA instead of Yaz0 (used in SZS files) for compression. The archive format is WU8 instead of U8 to allow small files without copyrighted material. The alternative compression should also help to avoid false positives of the copyright file scanners.

See »File format: U8 archives« for related file formats.


The file format WU8 (Wiimms U8) was developed by Wiimm to allow exchanging of custom tracks over the Internet without any Nintendo stuff and without license and copyright problems. The design is identical to the file format U8, but the sub files of the archive are patched against Nintendos original files.

WBZ and WLZ use the same file format and differ only in the type of compression. WBZ was introduced in 2012 and uses bzip2 for compression. WLZ was introduced in 2023 and uses LZMA, which is available from version v2.38a of Wiimms SZS Tools. Both alternative compressions should help to avoid false positives of the copyright file scanners.

File Format

The file format is very simple:

Offset Type Description
0x00 u32 The magic of WBZ: "WBZa" = 0x57425a61
The magic of WLZ: "WLZa" = 0x574c5a61
0x04 8 bytes Copy of the first 8 bytes of the decompressed data. This copy should help tools to find out the file format of the decompressed file without the need of decompressing it. An example is the command: wszst filetype of Wiimms SZS Tools.
0x0c u32 The size of the decompressed data in network byte order (big endian).
0x10 * bzip2 or LZMA compressed data.

Compression factors

bzip2 and LZMA supports the compression levels 1 to 9. For bzip2, level 9 is the best choice, because it produces the smallest files and is only a bit slower than the other level. A good way is to compress the data with level 1 and 9 and to use the smallest one. Wiimms SZS Tools do this.

For LZMA level 6 is the best choice. Level 6 has a dictionary size of 8 MiB. Higher levels have no advantages for tracks, but have disadvantages in memory usage.

File Extensions

Wiimms SZS Tools support these default file extensions:

archive format compression format file extension
U8 .u8
U8 Yaz0 .szs
U8 bzip2 .bz
U8 LZMA .lz
WU8 .wu8
WU8 Yaz0 .wu8
WU8 bzip2 .wbz
WU8 LZMA .wlz
all other type dependent
all other Yaz0 .szs
all other bzip2 .bz
all other LZMA .lz

Conversion in Windows

The newest version of Wiimms SZS Tools supports SZS from and to WBZ conversions via SendTo of Windows context menu. They also support WU8 as source.

  1. Install the current version of Wiimms SZS Tools.
  2. Install the SendTo extension with: install-sendto.bat.
  3. If not done, create the autoadd library:
    1. Extract the directory /Race/Course of the Mario Kart Wii DVD.
    2. Select the extracted directory with a right click and call SendTo | create-autoadd-library.
  4. Now you can convert each SZS and WBZ by using SendTo | convert-*.

You can also use the WBZ Converter.


The following tools can handle WBZ files: