rom-weaver

Trim a ROM in the browser

Use Trim to remove unused padding from a Nintendo DS/DSi, Game Boy Advance, Nintendo 3DS, or Xbox XISO image and download a smaller copy, or to pad a trimmed ROM back to full size. Keep the original for future patches.

Open Trim

  1. Open Trim. No setting needs to be enabled first.
  2. Add the ROM or its archive. The drop zone lists the accepted file types by platform: Nintendo DS/DSi, Game Boy Advance, Nintendo 3DS, and Xbox XISO, plus archives.
  3. Select the required member if an archive contains several candidates.
  4. Wait for reading, checksumming, and identification to finish.

Once the ROM is staged, the output step states what the run will do for that file. A file Trim does not support gets a notice instead; use Compress for other files. The trim support reference lists supported formats and restoration limits.

Save a trimmed copy

  1. Check the selected file in the ROM card. Open Checks to record its original checksums.
  2. Choose an output name and format.
  3. Select TRIM & DOWNLOAD. The run starts at once, or waits in the queue while the ROM is still being read.
  4. Read the warning dialog that opens, then select Got it. The dialog is informational: closing it, by button, Esc, or clicking outside, never cancels or changes the run.
  5. Save the result and test it in the emulator or hardware you use.

The format starts from the Download format setting in Settings: ZIP for Nintendo DS and Game Boy Advance ROMs and Z3DS for Nintendo 3DS ROMs by default, .7z or the plain file if you chose those there. Change it in the output step for one run.

GameCube and Wii discs cannot be trimmed: Trim flags them when staged and keeps the button disabled. An archive that holds only discs is flagged from its file list and the discs' first bytes, without extracting them. Convert them to RVZ with Compress instead.

The format list offers the ROM's own extension, ZIP, and 7z. Z3DS appears only for a 3DS ROM, and CHD is never offered for an Xbox XISO, which cannot be stored as CHD. A 3DS ROM is trimmed from inside a .z3ds, .zcci, .zcxi, ZIP, or 7z file; a .z3ds or .zcci input keeps its own extension.

A trimmed NDS, GBA, or 3DS ROM ends in a 12-byte revert marker that records the removed padding, so Restore padding can rebuild the original exactly. Tools that read only the ROM's used data ignore it; the footer format describes its limits. An XISO is rebuilt without its unused space and cannot be restored, so keep the original.

A file without removable padding may have no useful size reduction. A format that is not supported cannot be made trimmable by renaming it.

Restore padding

Add a trimmed ROM and Trim selects Restore padding for it; use the mode toggle in the output step to choose between trimming and restoring. RESTORE & DOWNLOAD also starts at once and opens a warning dialog.

Restoring is byte-exact only for a ROM trimmed with a revert marker, which browser Trim always writes for NDS, GBA, and 3DS ROMs. Without one, the padding is rebuilt as 0xFF: a 3DS cart image grows to the card size recorded in its header, a .cxi stays unchanged because it has no cartridge padding, and other ROMs grow to the next power-of-two size, which may not match the original. XISO trimming does not support restore-padding. A ROM trimmed with the CLI carries a marker only when you passed --revert-marker; see Trim and restore from the CLI. Compression and trimming explains the difference.