sms / gg header editor — free browser tool | fatcousin

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edit sega master system and game gear rom headers · tmr sega · product code · version · region · checksum auto-recompute · runs locally

drop rom

drop an sms or gg rom

.sms · .gg · Sega Master System or Game Gear ROM

Select file

status

drop an sms or game gear rom to edit its sega header

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.