BuildID (aka. BID), is an essential part of cheat. Each game version has its own build ID and a update would change that. There used to be PC tools like NSC_BUILDER (NSCB) to read buildID without switch hardware. But those are obsolete now and usually you have to use homebrew apps like EdiZon-SE or overlay to check that.

After months of search, I finally found a feasible solution to check buildID without switch. All you need is a hex editor and dumped (decrypted) content. It comes from masagrator on GBAtemp forum in a post titled Finding the Build ID for the cheats code.

The main idea is to extract buildID from main file in exefs. It locates at offset 0x40 and is 32-byte long (aka. 0x40 - 0x47). Cheats only use first 8 bytes.

ImHex Preview

If you wanna try it out yourself, an ideal test title is Fire Emblem: Shadow Dragon and the Blade of Light included in the FC/NES library offered by Nintendo Switch Online. It’s less than 20 MB and has no update/DLC. I would not go into detail about resource unpacking et al since that’s not the point of this post. But I can offer a hint: required main file is located in the largest file with nca extension.

Game info FYI, focus on BID:

• Fire Emblem: Shadow Dragon and the Blade of Light
• Version: 1.0.0
• TID: 0100A12011CC8000
• PID: 152
• BID: 48AE624761201F7

Update: just noticed you could use NxFileViewer to view it directly… Anyway, this still serves as a technical reference.