3DS:Save Data Transfer Tool

Save Data Transfer Tool is an official application made by Nintendo. It allows users to transfer the game save data from game cartridges to a title installed on the SD card. This can come in handy if you want to migrate from a game cartridge to a title installed on your SD card. It should be noted that after transferring the save data from the game card, the save data is wiped on the cartridge.

Alternatives
Due to Nintendo shutting down the eShop on the 3DS, this tool is no longer downloadable for new users. Luckily, there are Homebrew alternatives available for save data transferring. The easiest being save-data-copy-tool, while more advanced options like Checkpoint and JKSV allow for more dumping options.