Google says its AI payment protocol isn't locked to credit cards — so what else can it actually pay with?

This explores whether AP2 only works with cards or whether it also covers other ways of paying. The collection does not list AP2's supported payment methods, so it can't answer that directly. Google's public launch material describes AP2 as payment-agnostic. It names cards, real-time bank transfers and stablecoins, with crypto support added through an extension built with Coinbase. None of the notes here confirm or discuss that list. What the notes do explain is why AP2 can be agnostic about payment methods in the first place, and that turns out to be the more interesting part.

AP2 doesn't move money itself. It records who authorized what. A user's signed Intent Mandate ("buy running shoes under $120") is chained to a signed Cart Mandate ("these exact shoes, this price"), which creates a tamper-proof record of what the user agreed to before any payment happens How can signed mandates prevent payment fraud by agents?. Because the protocol proves consent rather than carrying the payment, any payment method can sit underneath it. This fits the IMF's argument that agent payments should keep the AI's unpredictable decision-making separate from the predictable, legally enforceable layers where authorization and settlement happen Should AI agents make payment decisions independently?. McKinsey makes a similar case: fraud systems used to rely on seeing a human click "buy," and signed mandates can take over that job Does agent-initiated commerce break existing payment infrastructure?.

So the more useful question is which payment methods agents will actually use, and in what order. Simon Taylor offers a sequence. First come virtual cards, because they already have spending controls and every merchant accepts them. Next come stablecoin-settled cards, which fix slow cross-border settlement. Last come native stablecoin wallets Will agents adopt cards before stablecoins for payments?. The last stage matters for multi-agent systems. A master agent can create a programmable sub-wallet with its own spending rules for each sub-agent, with no bank approval needed, and virtual cards can't do that at machine speed Can stablecoins let agents create spending authority without approval?. A protocol built around signed authorization records can sit on top of all three stages.

It also helps to see where AP2 sits among the other protocols. Stripe and OpenAI's Agentic Commerce Protocol solves a different problem: a single-use token, limited to one merchant and one cart total, lets ChatGPT pay without seeing card details Can payment tokens let AI agents checkout safely?. Visa's Trusted Agent Protocol lets merchants verify which agent they are dealing with Can cryptographic signatures help merchants identify trusted AI agents?. Boboev argues these protocols are layers that merchants combine, not rivals. In that picture, AP2 is the governance and accountability layer, not the payment rail Do agentic commerce protocols compete or complement each other?. The takeaway is that the payment-method question is mostly settled at a different layer. AP2's job is proving the user said yes, however the money ends up moving.