Can You Pay a Credit Card With Another Credit Card?
Why direct payment is blocked
Credit card issuers require bill payments to come from a bank account (checking or savings), not another credit card, so there is no option to type in a second card to pay the first. This is by design, since paying debt with more debt at card interest rates would be a fast way to spiral.
The balance transfer alternative
What you actually want is usually a balance transfer: moving a balance from a high-rate card to another card, ideally one with a 0 percent intro APR. You pay a transfer fee of about 3 to 5 percent, but escape interest during the intro period, which is the legitimate way to shift card debt.
Third-party workarounds
Services like Plastiq let you charge a card to send a payment, but they add a roughly 3 percent fee and the destination usually cannot be a credit card anyway. For a genuine cash crunch, a personal loan or a balance transfer beats any card-pays-card trick. Avoid using cash advances to pay another card, since interest starts immediately.