Saferoms Highly Compressed 〈LEGIT BLUEPRINT〉
In jurisdictions like the United States, the DMCA (Digital Millennium Copyright Act) prohibits downloading ROMs you do not own. However, if you own the original cartridge or disc, you are legally entitled to a backup. Highly compressed ROMs facilitate this. If you own Final Fantasy VII on PS1 (4 discs), you can legally download the CHD version from Saferoms as a backup, provided you do not distribute it.
If you truly want a compressed, safe library, skip the sketchy aggregators and do this instead: saferoms highly compressed