|Ahezard, shutterbug2000, and Rocket Robz
nds-bootstrap is a free and open-source homebrew application that allows homebrew, DS, and DSi ROMs to be launched natively rather than through emulation. nds-bootstrap works on the Nintendo DSi and 3DS through CFW, and on the Nintendo DS through a flashcart.
nds-bootstrap supports most DS and DSiWare ROMs with pretty high compatibility (see the compatibility list), however it's still not perfect. It offers some features like cheat support, overclocking the CPU for faster loading times (doesn't work on all games), running games that support it in DSi Mode (camera and WPA Wi-Fi features), and an in-game menu allowing for viewing RAM and taking screenshots. It also supports many older homebrew applications that don't natively work from the DSi/3DS internal SD card, including games like DSCraft. It also works on flashcards, called "B4DS mode" (bootstrap for DS), but with lower compatibility and only supporting DS mode. Compatibility in B4DS mode can be improved using a DS Memory Expansion Pak. B4DS mode also allows running several DSiWare from flashcards, even on DS/DS Lite.
Technically a frontend isn't required as nds-bootstrap uses an ini file to load its parameters, however it is recommended.
TWiLight Menu++ is the main frontend for nds-bootstrap developed by Rocket Robz. It has 6 customizable themes to choose from (the DSi Menu, 3DS HOME Menu, SEGA Saturn menu, Homebrew Launcher, original R4 kernel, and a Game Boy Color-esque menu) and includes a number of Anti-Piracy patches.
Makes it so the game can be launched through the HOME menu instead of navigating through TWiLight Menu++. If you experience issues then try editing per-game settings by holding Y while loading the forwarder or switch over to TWiLight Menu++. On 3DS there are two options, NDSForwarder and YANBF, YANBF forwarders are installed as 3DS-mode applications so they count towards the 300 title limit instead of the smaller 40 title limit on DSi-mode applications, however they cannot have animated icons and take slightly longer to load.