What Is Custom Firmware (CFW) on 3DS and What Can It Do?

Custom firmware (CFW) on the Nintendo 3DS is a full software modification that gives you control comparable to "administrator access" on a computer. Instead of being limited to what Nintendo allows, a CFW console can do anything the hardware is physically capable of. The 3DS Hacks Guide describes it as a complete modification from stock to boot9strap, and it is the reference resource for installing it.

What CFW actually changes

On a stock 3DS, the system only runs software Nintendo has signed and approved. CFW removes that restriction at the system level, so the console will run unsigned software and no longer enforces the region lock. That single change is what makes everything else on this list possible.

What you can do with CFW

According to the 3DS Hacks Guide, popular uses include:

• Running homebrew software and games made for or ported to the 3DS
• Bypassing the region lock, so you can play games from other regions
• HOME Menu customization with community-created themes and badges
• Modifying games ("ROM hacks") through LayeredFS
• Editing, backing up, and restoring save data
• Emulating older consoles, plus native playback of DS and GBA games
• Installing physical cartridges for digital use

What the guide installs

The 3DS Hacks Guide is not just an explanation — it walks you through a specific setup on unmodified retail 3DS/2DS consoles:

1. boot9strap and Luma3DS custom firmware are installed on the console.
2. Luma3DS automatically removes the region lock and allows unsigned software to run.
3. Homebrew software is added, such as a package installer, a save file manager, and a homebrew app store.
4. Critical system file backups are made, which can help avoid bricks and recover data if something goes wrong.

What the online service shutdown means for CFW

Nintendo 3DS online services have shut down, but the guide notes this does not affect modding:

• Current 3DS modding methods are unaffected.
• Internet access for homebrew applications (such as Universal-Updater) still works.
• The browser and general internet access still work.
• Only Nintendo Network online services, such as official game servers, are down. Alternate servers like Pretendo Network are a work in progress.

Before you start

The guide's own advice is to thoroughly read all introductory pages before proceeding. If you are deciding whether CFW is worth it, the answer depends on what you want: region-free play, save backups, emulation, and homebrew all require it, while a stock console cannot do any of them. If you only play official games online, note that official servers are already gone regardless of whether you mod.