UCP radar · public data from /.well-known/ucp
Mercatian.

Guide · Universal Commerce Protocol

What is UCP?

The Universal Commerce Protocol (UCP) is the open standard that lets AI agents — like Gemini or shopping assistants — discover stores, query catalogs and complete purchases without the customer ever visiting the merchant's site. It is backed by Google and Shopify together with Walmart, Stripe, Visa and Mastercard, and since January 2026 it has been redefining how people buy online.

Who is behind it

UCP was unveiled on January 11, 2026 at NRF (New York) as an open, community-driven protocol. Google brings distribution (Search AI Mode, Gemini), Shopify the installed merchant base, and the payments ecosystem — Stripe, Visa, Mastercard and, in Europe, signals like Klarna's endorsement — the transaction layer.

How it works under the hood

A store adopts UCP by publishing a JSON profile at /.well-known/ucp. That profile declares everything an agent needs to know:

  • capabilitieswhat the store can do: checkout, cart, catalog search, discounts, fulfillment…
  • servicesthe endpoints where agents talk to the store, and over which transport (REST, MCP, embedded).
  • payment_handlershow to pay: Google Pay, cards, ecosystem wallets.
  • supported_versionsthe protocol versions the store keeps alive.
{
  "ucp": {
    "version": "2026-04-08",
    "services": {
      "dev.ucp.shopping": [
        { "endpoint": "https://store.example/api/ucp/mcp",
          "transport": "mcp" }
      ]
    },
    "capabilities": {
      "dev.ucp.shopping.checkout":       [ { "version": "2026-04-08" } ],
      "dev.ucp.shopping.cart":           [ { "version": "2026-04-08" } ],
      "dev.ucp.shopping.catalog.search": [ { "version": "2026-04-08" } ]
    },
    "payment_handlers": {
      "com.google.pay": [ { "config": { "merchant_info": { } } } ]
    },
    "supported_versions": { "2026-01-23": "…", "2026-04-08": "…" }
  }
}
Real (trimmed) UCP profile from a Shopify store

The rollout calendar

  1. Jan 2026

    Launch at NRF

    Google and Shopify unveil UCP with Walmart, Stripe, Visa and Mastercard. First verified stores in the US.

  2. May 2026

    Google Marketing Live

    UCP-powered checkout goes live with major US retailers and Google announces expansion to Canada and Australia.

  3. Jun 2026

    Australia

    The rollout leaves North America.

  4. Late 2026

    United Kingdom

    The first European stop confirmed by Google.

  5. 2027?

    Continental EU and Spain

    No official date. Adapting to PSD2 (strong customer authentication), withdrawal rights and the AI Act will set the pace — and the signals suggest the machinery is already moving.

Final stage is Mercatian's estimate from public signals; the rest are milestones announced by Google.

What about Spain?

Spain will arrive with the continental EU wave, with two particularities: European regulation (PSD2 SCA, 14-day withdrawal rights, AI Act milestones from August 2026) and a local payments ecosystem where Bizum — 27M+ users — still has no UCP handler. Whoever shows up prepared captures agentic demand from day one.

What your store can do today
  1. 01Check whether your platform already publishes a UCP profile (Shopify does it automatically).
  2. 02Get on the radar: submit your domain and track your UCP Score.
  3. 03Follow the European rollout with Mercatian's data and quarterly report.
Add your store →Explore the directory

Sources and further reading