Key Takeaways
- ACP and AP2 are different layers, not competing standards. — ACP is the commerce/checkout protocol; AP2 is the payment-consent protocol. A full agentic purchase uses both — the agent checks out via ACP and proves authorization via AP2.
- ACP is maintained by OpenAI and Stripe. — It is an open standard, currently in beta, for connecting a buyer’s agent to a merchant to complete a purchase — the checkout handshake of agentic commerce.
- AP2 came from Google and is now community-governed. — Announced September 2025, AP2 uses verifiable digital credentials and cryptographic mandates for tamper-evident consent. Google released v0.2 and donated it to the FIDO Alliance on April 28, 2026.
- The card networks sit on top of both. — Visa’s Intelligent Commerce Connect (April 8, 2026) is a protocol-agnostic on-ramp accepting multiple agent standards at once; Mastercard’s Agent Pay framework does the equivalent on its rails.
ACP and AP2 do different jobs
The "ACP vs AP2" framing is misleading: they are not competing standards, they are two layers of the same stack. ACP is the commerce protocol — the checkout handshake between an agent and a merchant. AP2 is the payments protocol — the proof that the shopper authorized the spend. A complete agentic purchase uses both. Read them as checkout and consent, not as alternatives.
ACP — the checkout layer
ACP — Agentic Commerce Protocol is maintained by OpenAI + Stripe. Checkout: connects a buyer’s agent to a merchant to complete a purchase. Open standard, in beta. Its job is to make a store discoverable and buyable by an agent: the agent calls the protocol to complete a purchase rather than scraping a website. A companion standard, UCP (Universal Commerce Protocol), extends the same idea across the full commerce lifecycle, not just the moment of checkout.
AP2 — the payments layer
AP2 — Agent Payments Protocol came from Google → FIDO Alliance. Payment consent: verifiable credentials + cryptographic Mandates proving the user authorized the spend. Announced Sept 2025; v0.2 donated to the FIDO Alliance Apr 28, 2026. The mechanism is the important part: a cryptographic mandate creates tamper-evident proof of consent at every step, so an agent cannot spend outside what the user explicitly authorized. The move to the FIDO Alliance puts governance in a neutral, multi-vendor body — the same lineage as the passkey standards.
Where Visa and Mastercard fit
The card networks provide acceptance on top of the protocols. Visa’s Intelligent Commerce Connect, shipped April 8, 2026, is a protocol-agnostic on-ramp that accepts agents across several standards at once; Mastercard’s Agent Pay framework does the equivalent. For a merchant this lowers the betting risk: rather than picking the one protocol that wins, you accept agents through a network on-ramp that already spans multiple standards.
What a merchant actually does
Integrate the checkout layer first so agents can transact with you; then wire the payments layer so authorization is provable and clears. The agent-ready groundwork — clean product data and a callable checkout — is covered in the agentic commerce hub. For who is doing the buying on the other side of these protocols, see AI shopping agents. Protocol facts last verified 2026-06-10; this stack is moving fast.
Is AP2 a replacement for ACP?
No — they operate at different layers and are designed to work together. ACP (the Agentic Commerce Protocol, maintained by OpenAI and Stripe) governs the commerce interaction: how an agent and a merchant complete a checkout. AP2 (the Agent Payments Protocol, from Google) governs the payment: proving, with verifiable credentials and a cryptographic mandate, that the user authorized that specific spend. A complete agentic purchase typically uses ACP to transact and AP2 to authorize.
Who controls each protocol?
ACP is maintained by OpenAI and Stripe as an open standard, currently in beta. AP2 originated at Google, was announced in September 2025, and was donated to the FIDO Alliance on April 28, 2026 (with a v0.2 release), moving it to community governance. The shift to FIDO matters because it signals AP2 is meant to be a neutral, multi-vendor standard rather than a single company’s product.
Where do Visa and Mastercard fit?
They provide the card-network acceptance on top of the protocols. Visa shipped Intelligent Commerce Connect on April 8, 2026 — a protocol-agnostic on-ramp that accepts agents across multiple standards (Visa TAP, Mastercard MPP, ACP, UCP) simultaneously. Mastercard runs an Agent Pay merchant-acceptance framework. Their role is to let an agent pay on existing rails while the trust and consent are carried by AP2-style mandates.
Which protocol should a merchant integrate first?
Integrate the commerce layer first — adopt the checkout protocol (ACP, plus UCP for the broader lifecycle) so an agent can discover and buy from you at all. Then wire the payments layer so authorization is provable and clears on card rails. In practice the card networks’ protocol-agnostic on-ramps reduce the lock-in risk: you can support multiple agent standards through one acceptance integration rather than betting on a single protocol winning.
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