Converting between in-game save formats

On real hardware, Nintendo 64 saves are big-endian. Most emulators use little-endian saves, in-line with the fact that most PCs use little-endian architectures. N64 emulators for the Nintendo Wii, another big-endian platform, are one of the few cases where real hardware and emulator saves are directly compatible. At least one emulator, RetroArch's Mupen64Plus-Next, uses a different save format entirely from the N64 and other emulators.

If you're looking to convert between various real-hardware and emulator save formats, these are the tools you'll need. These operations are entirely reversible, so you can move your saves in either direction.

Going from real hardware to most emulators and vice versa

To swap between N64 (or Wii) saves and most emulators' (e.g. Project64 and non-RetroArch versions of Mupen64) saves, you can use either of the following tools:

Windows GUI: ED64-SaveSwap by saturnu

Python (cross-platform): saveswap by ssokolow

Simply select to byte- and word-swap your files to convert your files between formats expected by real hardware and most emulators. This is the default behavior of both tools, and the process is the same in both directions.

Going to and from Mupen64Plus-Next saves

RetroArch's Mupen64Plus-Next uses its own custom save format completely different to what you'll find on N64 or other emulators. If you're starting from a real hardware N64 save, you will first need to convert your save to little-endian using one of the above tools. If you're moving to RetroArch from another emulator, your save is most likely already little-endian.

With your LE save file ready, you can now use the following tool to convert to RetroArch's custom save format. Simply drag and drop your save file onto the executable.

Command-line, Windows build provided: pj64tosrm by heuripedes

You can also drop a Mupen64Plus-Next save onto the same executable to extract a little-endian flash save compatible with other emulators or the above endian-swapping tools if you wish to use the save on real hardware.