I've never heard of a totally free interest free credit card.
Without the interest charged by the credit card companies the credit card companies would not make any money from lending you the money on the credit card.
I've heard of some credit cards that offered no interest for the first 6 months to the first year on the credit card which was an introductory offer to get you started with the credit card.
Usually though to get approved for that interest free credit card you need excellent credit.
But after the first 6 months to a year of using the interest free credit card you then are charged interest on the credit card.
If you find a totally interest free credit card offer then it's likely a scam because there's no way they could offer no interest on the credit cards forever.
I've had calls offering me totally interest free credit cards and interest free loans but those are scams as they cannot make any money with charging no interest at all.