The product is pretty interesting. I have/love Simple, but the two seem pretty different. Zero appears to be technically a credit card, whereas Simple is a debit card.

I rarely use a credit card because it is just too easy to overspend. The only safe way to avoid that would be to use your credit card a 100% of the time. Of course then you have to routinely check your checking account balance. As enticing as cash back is, it has never seemed worth that risk/hassle. This does seem to solve that problem. However this company is in way too early of a stage to rely on. Simple has been around for several years.

Would love a metal card though...