.well-known/ucp

What is the ucp file?

A profile document at https://yoursite.com/.well-known/ucp (no .json extension) that declares your site's commerce posture in Universal Commerce Protocol terms. For commerce-enabled customers, it is populated with your commerce capability profile; for non-commerce customers, we emit a minimal "no commerce" profile with a comment explaining the placeholder.

Why AI agents need it

Agentic commerce is moving from demo to infrastructure: AI surfaces are beginning to complete purchases on users' behalf, and they need machine-readable answers to "can I transact here, and how?" A published UCP profile is the standard-shaped answer, including the honest answer "this site does not sell online," which saves agents from probing for a checkout that doesn't exist.

The business value for you

Commerce sites position themselves for the buying flows being built into major AI surfaces. Non-commerce sites get accuracy: agents stop guessing about your commerce capability because you've declared it. Either way, your profile is legible in the vocabulary the largest players are converging on.

How it came to be

Google launched UCP in January 2026 at NRF Retail's Big Show, co-developed with Shopify and with partners including Walmart, Target, Etsy, Adyen, Mastercard, Stripe, and Visa. It is an open-source standard (published at ucp.dev) designed to work across the shopping journey, catalog, cart, checkout, orders, and to interoperate with the other agent protocols in this package's ecosystem: A2A, MCP, and the Agent Payments Protocol.

Sources: Google for Developers, Getting started with UCP • Google Open Source Blog, Open rails for agentic commerce (June 2026)

Adoption

Young but heavyweight. UCP is pre-1.0 and evolving, with Google's own reference implementation powering direct purchases in AI Mode in Google Search and Gemini, and early merchant adoption concentrated on large platforms (Shopify stores account for the bulk of verified UCP storefronts so far). The partner roster, major retailers plus the payment networks, is the signal that this is infrastructure being laid, not a press release.

Source: Google Developers Blog, Under the Hood: Universal Commerce Protocol

The technical reality

Full UCP participation (live checkout inside AI surfaces) requires server-side integration and, for the Google implementation, a Merchant Center account. That is real engineering work beyond static files. What the package ships is the static profile layer: a well-formed .well-known/ucp document that declares your posture truthfully. Related server-side commerce protocols (x402, AP2, ACP) require running endpoints and are planned for a later release. We leave those as future work. Static files do not fake live endpoints. The spec is pre-1.0, so the managed subscription tracks upstream changes and refreshes your profile.

What happens if you skip it

Commerce agents get no declared answer about your site. For a store, that means absence from the discovery layer of the buying flows being built now; for a service business, it means agents keep guessing about a capability you could have clarified in one file.