patch creator — free browser tool | fatcousin

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diff two roms and generate an ips or bps patch · for rom hacks and translation patches · runs locally

original rom

Drop the unmodified (original) ROM

the base file — before any edits

Select file

modified rom

Drop the edited ROM

the version with your changes applied

Select file

format

IPS — classic · max 16 MB · universal compatibility

status

drop original rom, then modified rom

create

format info

IPS (International Patching System) — the classic format. Simple 24-bit records covering up to 16 MB. Universal compatibility with patchers like Lunar IPS, MultiPatch, BEAT. RLE-encoded for compact runs.

BPS (Beat Patch System) — the modern standard. Supports files up to 64.00 MB in the browser. Hash-table delta compression finds matching regions across the whole ROM — smaller patches than IPS for large ROMs. CRC32 checksums on source, target, and patch for integrity verification.

notice

you supply your own files. fatcousin does not host, link to, or recommend sources for rom files, bios files, or copyrighted game data. this tool is for preservation, modding, research, and education with files you lawfully possess. all processing runs in your browser — files never leave your device.