3DS Import/Export NDS Cartridge Saves

Importing and exporting saves from legitimate NDS cartridges using 3DS homebrew software, including importing flashcart saves to legit cartridges.

Fig 1 · Test cartridge family photo

Multiple cartridges were tested to ensure stability: JUMP Ultimate Stars (JP), JUMP Super Stars (JP), Mario 64DS (JP), and SimCity 2 (EU).

Fig 2 · Four test cartridges

Mario 64DS Test

First, testing Mario 64DS — as you can see, there are no saves at all.

Fig 3 · Mario64DS — blank save

Fig 4 · Mario64DS main menu

R4 Flashcart

Now let's switch to the R4.

Fig 5 · R4 flashcart

Select the Japanese Mario 64DS.

Fig 6 · Select Japanese Mario64DS

The save has two 120-star files.

Fig 7 · Save has two 120-star files

PC Operations

OK the R4 is done, let's switch to the PC. Find the save location on the R4 card (same directory as the game).

Fig 8 · Save file on R4 card

The save size is 512KB — I'll explain this in detail later.

Checkpoint Backup of Legit Cartridge Save

Open the 3DS with Checkpoint.cia installed — I won't demonstrate the installation here. There's also a software called NDS Save something, with the same functionality, so I won't elaborate.

Fig 9 · Checkpoint loading

First launch takes a while to load. After loading, select the NDS position, hold L and press A — it will ask if you want to backup — just press A.

Fig 10 · Hold L + A to backup save

After backup, power off and remove the 3DS SD card, insert it into the PC. You can also use 3DSFTP for this.

The backup file is in the

3DS\Checkpoint\saves\Game Name\Backup Date

folder, in .sav format.

Fig 11 · Checkpoint backup save file

Save Size Differences & Conversion

The exported save file is 8KB, which doesn't match the flashcart save size — now we need PC software.

Fig 12 · Save size: legit 8KB vs flashcart 512KB

Fig 13 · Top: legit cartridge save, Bottom: flashcart save

Rename the flashcart save file to .dsv — because this software only recognizes .dsv format saves.

Fig 14 · Save file renamed to .dsv

Open the software, find the renamed save, change output format to Other, change size to 8KB (matching the legit cartridge size — if the legit cartridge save exported as 512KB, select 512KB here). Then click convert. Open the save location to see the converted file.

Fig 15 · Save conversion software operation

Fig 16 · Successfully converted save file

Import to Legit Cartridge

Rename the file to match the legit cartridge's filename, replace it in

3DS\Checkpoint\saves\Game Name\Backup Date,

reinsert the SD card into the 3DS and boot up.

Open the software on 3DS, select the previously exported save, hold R then press A, confirm. It might freeze briefly during import.

This prompt only appears on successful import:

Fig 17 · Import successful!

Then open the game to verify — two 120-star files, matching the flashcart save.

Fig 18 · Two 120-star files, import successful

Test Results & Notes

After testing, all four games below work without issues.

Fig 19 · All four cartridges running normally

However, note: saves from fan-translated games CANNOT be imported to legit cartridges — this may corrupt the cartridge save!

The complete workflow:

Save size is the key — legit cartridge .sav exports are actual EEPROM/Flash sizes (usually 8KB or 512KB), while flashcart saves are in a uniform 512KB format. The conversion software trims/pads the flashcart save to the legit cartridge's actual size.