Question 1

What is x402?

Accepted Answer

x402 is a pattern for paying for an HTTP request using the 402 Payment Required status code. The server answers an unpaid request with 402 and a machine-readable description of what payment it wants — amount, asset, recipient, chain. The client pays and retries with proof of payment attached. It matters for AI agents because it needs no account, no API key issued in advance and no human in the signup flow: a wallet is sufficient to become a paying customer.

Question 2

Can an AI agent pay for something without a credit card?

Accepted Answer

Yes, if the service accepts payment in a form the agent can produce. A crypto wallet is the practical option, because an agent can hold one and sign with it unattended, whereas card payments assume an account holder, a billing address and often an interactive verification step. This is why machine-payment schemes converged on wallet signatures rather than on card rails.

Question 3

Does an agent need to pay gas to make a paid API call?

Accepted Answer

Not necessarily. With a signature-based authorisation such as EIP-3009, the agent signs an off-chain message authorising a transfer, and the service submits the resulting transaction and pays the gas itself. The agent needs the payment asset but no native gas token on the settlement chain, which removes an entire class of setup problem — an agent funded in stablecoins but not in gas can still transact.

One post tagged with "machine-payments"

How does an AI agent pay for an API call?