Build Nintendo Switch XCI and HFS0 files
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LucaFraga This should fix Issue #5 for good now.
Removed all possibilities of UInt32 overflow
Latest commit 6ca45e9 Jun 30, 2018
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hacbuild This should fix Issue #5 for good now. Jun 29, 2018
.gitignore Initial commit Jun 27, 2018
LICENSE Initial commit Jun 27, 2018 Update Jun 28, 2018
hacbuild.sln Initial commit Jun 27, 2018


hacbuild is a Work-In-Progress utility to rebuild Switch GameCards (XCI) from scratch.



  • hacbuild hfs0 <in_folder> <out_file> Builds a hfs0 partition
  • hacbuild xci <in_folder> <out_file> Builds a XCI from a directory containing 'root.hfs' and 'game_info.ini' (optional)
  • hacbuild xci_auto <in_folder> <out_file> Builds a XCI from a directory containing the folders 'normal', 'secure', 'update' and 'logo' if needed. 'game_info.ini' is also used.
  • hacbuild read xci <in_file> Reads a XCI, displays info on the console and dumps the game .ini configuration (for game_info.ini) in the working directory.

The program will automatically seek a keys.txt file in the working directory in order to gather the only key needed: XCI Header Key (xci_header_key = 01C5...)


  • Rebuilds the XCI format
  • Rebuilds HFS0 partitions (with less padding than the official ones)
  • Reads XCI files to obtain informations needed to rebuild them
  • Can ULTRA-trim (still experimental) XCIs by removing the entirety of the update partition (leaving at least one file) and having less padded HFS0


  • Can't generate a valid RSA signature for the XCI, so they can only be loaded with kernel patches
  • Still can't figure out the usefulnes of some fields
  • Due to NCAs signature checks we still can't modify games (for example eShop titles can be mashed into a XCI but they will still require a ticket)
  • The coding is quite dirty and it lacks pretty much any exception handling. Use with care

Help needed

We have pushed hacbuild to a state where it can build valid XCI files, but there is still very much to do. Since we know the potential is there, we'd like people to contribute to the project.

Credits & useful links

hacbuild was inspired by:

We'd also like to thank SwitchBrew for their extensive research and documentation of the Nintendo Switch.