An open source 3DS homebrew app for downloading system update titles from NUS directly to the console (packed in CIA format). Based on code from 3DNUS and make_cdn_cia. License is GPL to comply with the usage of make_cdn_cia code. The code is simple enough to be integrated into a CIA installer to have a complete, but more flexible, alternative to the official system updater.
NOTE: since NUS does not host many of the pre-installed firmware titles, downloading a complete update pack for region changes cannot be done at this time.