Google's UCP gets Cart and Catalog - but where is Europe in the protocol war?

While you’re still wondering whether your product data is machine-readable, Google is already laying the groundwork for AI agents to shop in the future. And no one in Europe is setting the course.

Cart and Catalog: UCP Comes of Age

Google updated the Universal Commerce Protocol (UCP) this week—the protocol the company unveiled in January at the NRF alongside Walmart, Shopify, Target, and Etsy. Three new features have been added:

• A Cart capability that allows agents to add multiple items to a shopping cart at once.
• A catalog endpoint through which agents can retrieve real-time product data—such as variants, prices, and inventory levels—directly from the merchant’s catalog.
• Identity linking, which makes loyalty programs and membership benefits available across platforms.

That sounds like technical details. But that doesn’t tell the whole story. Cart and Catalog are the building blocks that transform UCP from a checkout protocol into a complete commerce infrastructure. Whoever controls catalog access controls which products an agent even sees. Whoever controls the shopping cart controls the completion of the purchase. Google isn’t building a neutral pipeline here—Google is building the platform where agents and merchants are meant to meet. Added to this is a simplified integration via Google’s Merchant Center, which is set to roll out in the coming months—and which lowers the barrier to entry for smaller merchants. Or to put it another way: it accelerates lock-in.

Who’s at the table—and who isn’t?

UCP’s list of endorsers reads like a Who’s Who of U.S. retail: Walmart, Target, Best Buy, The Home Depot, Macy’s. Plus the payment giants Visa, Mastercard, Stripe, Adyen, and American Express. And Shopify as a platform partner, whose merchants can automatically use UCP via Agentic Storefronts.

Any European names? Zalando appears on the list. Otherwise: silence. No Shopware. No About You. No Otto Group. No European payment provider. No European platform contributing to the specification.

This is remarkable, because UCP is not a closed Google product. It is an open standard with a GitHub repository and a REST/JSON-RPC foundation. Theoretically, anyone can join. In practice, U.S. corporations define the architecture, and Europe is allowed to implement it later.

Counterproposals: AMP and the Agentic Commerce Alliance

At least something is happening—albeit not from Brussels. In mid-March, the London-based startup Azoma introduced the Agentic Merchant Protocol (AMP), a merchant-side layer that allows brands to control how their products are displayed in AI agents. Early adopters: Mars, L’Oréal, Unilever, Beiersdorf, and Reckitt—in other words, the FMCG companies that fear platform-driven protocols will erode their brand sovereignty.

Shopware founded the Agentic Commerce Alliance in July 2025, together with PayPal, Klaviyo, Trusted Shops, and the Italian payment provider Nexi. The alliance aims to create “open, interoperable standards” and is working on trust systems, scoped payments, and interoperable data formats. The right approach—but so far without its own protocol that could compete with UCP or AMP.

Meanwhile, the Paris-based startup Lemrock has raised 6 million euros to build middleware between merchant systems and AI agents like ChatGPT and Claude. Its clients include Darty, Leroy Merlin, Lidl, and Rakuten. So European startups are providing the translation layer—but the protocol layer beneath it remains American.

Where is the EU?

One might think the EU Commission had prepared for exactly this scenario. The Digital Markets Act (DMA) requires gatekeepers to ensure interoperability. In January 2026, the Commission launched proceedings against Google that explicitly concern interoperability and data-sharing obligations in online search.

But here lies the problem: The DMA regulates existing gatekeeper positions—search engines, app stores, messaging services. It does not regulate who writes the protocol through which AI agents will shop in the future. UCP is not a marketplace. It is not an app store. It is infrastructure that is just emerging. And the EU has no instrument for emerging infrastructure. The DMA review is scheduled for May 2026—but agentic commerce protocols are unlikely to be on the agenda while Brussels is still preoccupied with interoperability obligations for messaging services.

The AI Act, which takes effect for high-risk systems starting in August 2026, regulates transparency, risk management, and human oversight. Does a shopping agent that independently fills shopping carts and completes checkouts qualify as a high-risk system? That is still under negotiation. Until then, Google is creating facts on the ground.

The payment track is coming — from the U.S.

In parallel with the protocol expansion, Visa is building the payment infrastructure for Agentic Commerce. This week, the company launched Visa Intelligent Authorization (VIA) in Europe—an API that enables acquirers to access new payment methods, including Agentic Commerce, without completely overhauling legacy infrastructure. Launch partners: Comercia Global Payments, Elavon, Fiserv, UNICRE, and Worldline.

Visa promises “99.999% uptime” and an “average approval rate of 96.3% worldwide.” Those are impressive figures. But they obscure the real dynamics: The infrastructure through which autonomous agents will make payments comes from Visa and Mastercard. European acquirers are allowed to connect. Someone else determines the architecture.

To be fair: Visa is deliberately launching VIA with European partners and has simultaneously launched the Visa Agentic Ready program for European issuers—Barclays, HSBC UK, Nationwide, and Revolut are the first to join. But “agentic-ready” also means: the rules of the game have already been written; all you can do is play along.

The real question

Karen Webster of PYMNTS put it this way this week: What is being sold as a revolution in commerce is “for the moment, above all, a highly intelligent search bar.” That’s true—for now. But Cart and Catalog are gradually turning that search bar into a shopping assistant. And whoever writes the rules for this assistant determines which merchants remain visible.

In the U.S., Google, Walmart, and Shopify are negotiating these rules among themselves. In Europe, we’re forming alliances, raising seed rounds, and waiting for the next regulation. Who will write the rules by which your customers shop tomorrow—you, or a protocol from Mountain View?

(An LLM researched and wrote this. A human read it, edited it, and approved it. We’re still debating which of the two did more work.)