Four Agentic Commerce Frameworks Compared: Visa TAP, Google UCP and AP2, OpenAI ACP, Mastercard Agent Pay
Four companies are building agentic commerce protocols: the rails for AI agents to buy things. Only one in ten consumers will currently let one do it.
Mastercard’s Signals report “Encoding Trust,” published in August 2026, puts numbers on the gap. 85% of consumers are open to working with an AI agent to find the best option. 74% will let an agent complete a specific task on request. But only one in ten will let an agent complete a purchase autonomously, according to Gartner research from May 2026. Agent-assisted consumer spending is still forecast at $3 to 5 trillion by 2030.
Read the four main frameworks side by side and the surprise is that they are not really competing. They answer different questions.
Agentic Commerce Protocols at a Glance
| Framework | Question it answers | What it does |
|---|---|---|
| Visa Trusted Agent Protocol (TAP) | Is this agent legitimate? | Signs agent identity into HTTP requests |
| Google UCP and AP2 | What is being bought, and who approved it? | Discovery, cart and checkout, plus signed mandates |
| OpenAI ACP | Where does checkout happen? | Now mainly product discovery |
| Mastercard Agent Pay | What pays, and was it authorized? | Agent-scoped tokens and verifiable intent |
Visa TAP: Is This Agent Legitimate?
Built with Cloudflare, Visa’s Trusted Agent Protocol signs agent identity into HTTP headers using RFC 9421 message signatures. A merchant receiving a request can check that it really comes from a known, vetted agent and not a scraper or a bot pretending to be one. No money moves over TAP. It is a bouncer at the door, not a payment rail.
Google UCP and AP2: What Is Being Bought, and Who Approved It?
Google’s Universal Commerce Protocol covers discovery, cart and checkout, so agents can find products and build orders in a standard way. The Agent Payments Protocol (AP2) carries signed Intent, Cart and Payment mandates as W3C Verifiable Credentials. Together they create a record of what the user asked for, what the agent put in the cart and what payment was approved.
OpenAI ACP: Where Does Checkout Happen?
OpenAI’s Agentic Commerce Protocol asked a different question, and the answer changed. In-chat Instant Checkout launched in September 2025 and was pulled back in March 2026 after roughly 30 Shopify merchants went live. ACP survives as a discovery protocol. Checkout went back to the merchant.
That is an important data point. Merchants and payment providers pushed back on handing checkout to an assistant. The merchant’s own checkout, with its tokens, fraud tools and customer relationship, turned out to be hard to replace.
Mastercard Agent Pay: What Pays, and Was It Authorized?
Agentic Tokens extend Mastercard’s tokenization service (MDES) so a credential can be scoped to one agent, one merchant category and one spending limit. Verifiable Intent, open-sourced in March 2026 with Google, binds the cardholder’s original instruction to the transaction that results.
The quiet move is that Mastercard built its trust layer to be protocol-agnostic and explicitly aligned with AP2 and UCP. Whichever surface wins, whether ChatGPT, Gemini or a bank’s own app, the intent proof and the token still route through the network.
Pablo Fourez, Mastercard’s Chief Digital Officer, put it in four words: “trust becomes the product.”
Why This Matters for Authorization Teams
For anyone running authorization, this is the CIT/MIT problem again, at a much larger scale. In card payments, a transaction is either customer-initiated or merchant-initiated, and getting that flag right changes how issuers treat it. Agent transactions add a third party and a new question: what did the customer actually authorize the agent to do?
The data that answers that question, the signed intent and the agent identity, arrives outside the traditional authorization message. Issuers who cannot read that context will decline good traffic and file it as fraud. Merchants who cannot pass it along will see approval rates drop on agent orders without knowing why.
What to do now:
- Get network tokens in place for card-on-file. Agent tokens build on the same foundation. See Network Tokenization vs PCI Tokenization.
- Track approval rates for agent traffic separately from human traffic.
- Ask your processor which agent signals it can pass to issuers today.
- Plan dispute handling for agent-initiated orders before volume arrives.
More on measuring approval performance in my authorization rate optimization guide.
Who Owns the Agent Credential?
These agentic commerce protocols stack rather than compete: identity from TAP, intent and cart from AP2 and UCP, credential and authorization from the networks, discovery from assistants like ChatGPT. The open question is which layer ends up owning the agent credential: the network, the AI platform or the merchant.
Source: Mastercard Signals, Encoding Trust (August 2026).
Agentic Commerce Protocols: Key Takeaways
- The four agentic commerce protocols answer different questions: identity, intent, checkout and payment.
- Agentic commerce protocols stack rather than compete.
- Merchants should prepare network tokens and agent signals before agentic commerce protocols reach scale.
- Who owns the agent credential is the open question across all agentic commerce protocols.
FAQ
What is Visa Trusted Agent Protocol?
Visa’s Trusted Agent Protocol (TAP), built with Cloudflare, signs an AI agent’s identity into HTTP requests using RFC 9421 message signatures so merchants can tell a legitimate agent from a bot. No money moves over TAP.
What are Google UCP and AP2?
Google’s Universal Commerce Protocol (UCP) covers discovery, cart and checkout for agents. The Agent Payments Protocol (AP2) carries signed Intent, Cart and Payment mandates as W3C Verifiable Credentials to prove what the user approved.
What happened to OpenAI’s Agentic Commerce Protocol?
OpenAI’s in-chat Instant Checkout launched in September 2025 and was pulled back in March 2026 after roughly 30 Shopify merchants went live. ACP continues as a discovery protocol, with checkout returning to the merchant.
What is Mastercard Agent Pay?
Mastercard Agent Pay uses Agentic Tokens, an extension of Mastercard’s tokenization service, to scope a credential to one agent, one merchant category and one spending limit. Verifiable Intent, open-sourced with Google in March 2026, binds the cardholder’s instruction to the resulting transaction.
A shorter version of this analysis was first published on LinkedIn on August 27, 2026.