HzMod (or as more widely known HorizonModule, or HorizonM) is a sysmodule for the 3DS which runs in the background. It uses its own protocol which is not compatible with NTR streaming apps, but is supported by its own viewer, HorizonScreen (various versions are fully compatable with every HzMod version, but lacking features and user-friendliness), as well as Snickerstream (much better UI, but doesn't support TARGA frames for games which use 16-bit color mode, like Smash and Mario Kart 7) and Chokistream (a from-scratch re-implementation of Snickerstream which has limited TARGA support).

Note: No longer being developed. BootNTR Selector is somewhat still under development and serves largely the same purpose, and Snickerstream/Chokistream can replace HorizonScreen as described above.

• Framebuffer rendering received from HorizonM.
• An unfinished debugger (HzDbg).
• Runs natively.
• Old3DS-compatible screen streaming.

The all-in-one pack contains the following:

• HorizonM.cia or HzMod.cia - Base module only, does not show up in Home Menu.
• HzLoad.cia - This shows up in Home Menu, but this does not contain HzMod, this is only the launcher.
• HzLoad_HIMEM.cia - For Old3DS/2DS and if you plan on using extended memory games (if the backlight turns off for more than a few seconds when launching the game then it is most likely an extended memory game).
• HorizonScreen - PC-side viewer (source).