Citra is a work-in-progress Nintendo 3DS emulator/debugger started in early 2014 written in C++. Although it is slow at this time, it is constantly being improved. The Citra repositories are hosted on GitHub. Citra is licensed under GPLv2 (or any later version).
Citra’s features include better visual output, debugging homebrew, and controller support. Can currently emulate, with varying degrees of success, a wide variety of different homebrew applications and commercial software.