The real thing is any like this validator only checks if the NUBMER of a card is actually vailid builded by banks.
It doesnt checks if that card really Exists. You can try to write random valid build numbers, it will probably say you that its gucci, but in real it doesnt exists yet in the world.
Yeh for some FULLZ cc info it can be used to see if thats a gucci card numbers, but not the 100% way to valid it