Nand.bin Melonds Work -

file is a critical system file required for Nintendo DSi emulation

or by using the built-in DSi Menu features within the emulator to manage data. nand.bin melonds

MelonDS:

Legality: Ensure that any files you obtain or create comply with your local laws and Nintendo's terms of service.
Safety: Be cautious when downloading files from the internet, and consider creating your own nand.bin from a personal DS console if possible.

Conclusion