DownloadMii is an online marketplace for Nintendo 3DS homebrew applications and its 100% free of charge for the end-user. It is currently under development, and the GitHub project can be found here! You can read about the latest news, 3DS news and app releases/showcases here. To use DownloadMii, you will need a way to run .3dsx files on your Nintendo 3DS. The .cia format for the main application in the future, However DownloadMii will still only support downloading .3dsx applications.