GodMode9 Explorer by d0k3 is a full access file browser for the Nintendo 3DS console. It gives you access to your SD card, to the FAT partitions inside your SysNAND and EmuNAND and to basically anything else. Among other functionality you can copy, delete, rename files and create folders. You can find the source here.

Changes:

[new] Hardcoded readme and readme viewer inside the HOME -> More… menu
[improved] Vastly improved GBA VC Save injection method – will now work 100% of time
[improved] Improved image mount handling
[improved] Improved text viewer colour scheme
[improved] Improved FIRM decryptor (only applies to N3DS original FIRMs)
[fix] Fixed scripts not showing up in text viewer
[fix] Fixed crashes when viewing certain text files
[scripting] Fixed and improved shaget command