While many commercial sites host ROMs, the "Index of" format is preferred by power users for several reasons:
Additionally, the MAME project itself is moving toward emulating more modern hardware (Sega Naomi, PlayStation-based arcade systems), which requires CHD files (hard disk images) that are even harder to find legitimately. index of mame roms
The Multiple Arcade Machine Emulator (MAME) is the gold standard for preserving arcade history, supporting over 8,000 games. However, managing a vast "index" of ROMs can be daunting due to the sheer volume of data and the specific ways MAME organizes files. Understanding the MAME "Index" The Ultimate Guide to "Index of MAME ROMs":