libyaz0 – A library for compressing and decompressing Yaz0/1 compression formats.

libyaz0 is a library in Python for decompressing and compressing Yaz0/1 compression formats.
Written in Python 3.

Yaz0 is a compression format used in several games from the N64, GC, Wii, 3DS, Wii U, and now the Switch.

few of those games:

  • The Legend of Zelda: Ocarina of Time.
  • Super Mario Sunshine.
  • Mario Kart Wii.
  • Super Mario 3D Land.
  • New Super Mario Bros. U.
  • Mario Kart 8.
  • Breath of the Wild.
  • ARMS.
  • Splatoon 2.

I’d say it’s a Nintendo-favorite. :>


Example of how Yaz0 compressed data can be decompressed:

from libyaz0 import decompress

# Yaz0 compressed data
data = b"Yaz0\x00\x00\x00\x10\x00\x00\x00\x00\x00" \
          b"\x00\x00\x00\xfbThis \x10\x02a \xf8test!"

# Decompress it
decompressed_data = decompress(data)
>>> decompressed_data.decode('utf-8')
'This is a test!'


Example of how decompressed data can be Yaz0 compressed:

from libyaz0 import compress

# Decompressed data
data = 'This is a test!'.encode('utf-8')

# Compress it
## unk: the 4-bytes value that will be located at 0x8-0xC of the Yaz0 header
### default is 0x00000000
unk = 0

## level: compression level.
### 0: No compression (Fastest)
### 9: Best compression (Slowest)
#### default is 1
level = 9

compressed_data = compress(data, unk, level)
>>> compressed_data
b'Yaz0\x00\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00\x00\xfbThis \x10\x02a \xf8test!'


libyaz0 can also be used to guess the file extension from the decompressed data.

File formats libyaz0 can detect:

  • BNTX (.bntx)
  • BNSH (.bnsh)
  • BFLAN (.bflan)
  • BFLYT (.bflyt)
  • BFLIM (.bflim)
  • GTX (.gtx)
  • SARC (.sarc)
  • Yaz0/SZS (.yaz0)


from libyaz0 import guessFileExt

# Guess the file extension from the decompressed data
file_extension = guessFileExt(decompressed_data)


libyaz0 can also be used as a standalone program. (Download below)


  • libyaz0 [option…] input


  • -o <output>: Output file, if not specified, the output file will have the same name as the intput file
  • -c: Compress (Will try to decompress if not specified)

Compression options:

  • -level <level>: compression level (1-9) (1 is the default)
    0: No compression (Fastest)
    9: Best compression (Slowest)
  • -unk <unk>: the unknown value that will be located at 0x8-0xC (0x00000000 is the default)



You can get libyaz0 using pip:

pip install libyaz0==0.4

Or you could get the source code from GitHub.
Standalone program (Windows).


Written by AboodXD.
Decompression algorithm based on wszst’s.
Special thanks to RoadrunnerWMC for helping with looking up matches for the compression algorithm.