Definition
The Universal Commerce Protocol (UCP) is an open standard for agentic commerce that gives AI agents, merchants and payment providers a shared way to handle product discovery, checkout, order updates and post-purchase support. Google announced it on January 11, 2026 at the National Retail Federation show. It was co-developed with Shopify, Etsy, Wayfair, Target and Walmart and endorsed by more than 20 other companies, including Adyen, American Express, Mastercard, Stripe and Visa.
UCP belongs to the same family as OpenAI and Stripe's Agentic Commerce Protocol (ACP), but its scope is wider. ACP launched as the checkout layer for ChatGPT. UCP is pitched as a vendor-neutral standard for the whole shopping journey on any surface. Google says it is compatible with the Agent Payments Protocol (AP2), Agent2Agent (A2A) and the Model Context Protocol (MCP), and the specification defines REST, MCP, A2A and embedded transport bindings.
How it works
A business publishes a profile at /.well-known/ucp that lists the capabilities it supports and the transports it accepts. An agent platform fetches the profile, negotiates the capabilities both sides share, then calls them. The core capabilities in the published spec are:
- Checkout: create and update a checkout session, including cart contents and tax.
- Identity linking: OAuth 2.0 authorization so an agent can act for a signed-in customer, for example to apply loyalty benefits.
- Order: webhooks that push shipping, delivery and return updates back to the platform.
Payments run through payment handlers such as Google Pay or Shop Pay using tokenized credentials, and the retailer stays the merchant of record. The protocol is versioned by date (v2026-01-11, v2026-04-08 and v2026-08-25 so far) and governed through ucp.dev. Stripe joined Google and Shopify on the governing council in April 2026, and technical councils for food, lodging and payments formed between July and September 2026. A draft lodging booking capability, written with Amadeus, Booking.com, Expedia, Hilton, Marriott and Trip.com, was merged on September 25, 2026.
UCP on Google
Google built the first implementation: a checkout button on eligible product listings in AI Mode and Gemini, paid with Google Pay. Etsy and Wayfair were the first live merchants in the US in February 2026. At Google Marketing Live on May 20, 2026, Google added a Universal Cart that works across retailers, said UCP checkout would come to Shopping ads on YouTube and Direct Offers, and announced rollouts to Canada and Australia, then the UK. Hotel booking in AI Mode and food ordering in Google Maps are planned next.
To take part, a merchant needs an active Merchant Center account with checkout-eligible products. The UCP integration hub in Merchant Center lets merchants choose native checkout on Google, cart transfer to their own site, or identity linking, and validate each one in a sandbox. Google says the hub is rolling out gradually in the US, with Australia and Canada to follow next year.
Why it matters for AI search visibility
UCP turns an AI answer from a recommendation into a transaction. When a shopper can buy inside AI Mode, being named in the answer and having a checkout-eligible listing can matter more than the click to your site. For teams preparing for agentic commerce, most of the work is feed and operations hygiene: complete, accurate product feeds, correct shipping and return policies, and checkout endpoints that pass Merchant Center validation. Checkout only happens on products the AI chooses to show, so tracking whether your products appear in AI shopping answers stays the first step. Google's UCP developer guide covers integration, and the UCP announcements page tracks spec releases. For a practical checklist, see how ecommerce brands prepare for agentic commerce.
Examples of Universal Commerce Protocol (UCP)
- A home goods retailer already on Merchant Center implements UCP's three native checkout REST endpoints (create, update and complete a session), validates them in the Merchant Center sandbox, and starts showing a Google Pay checkout button on eligible listings in AI Mode.
- A Shopify merchant with a heavily customized checkout picks the cart transfer capability instead of native checkout, so shoppers build a cart in Gemini and finish payment on the merchant's own site.
- A hotel group maps its room availability, guest details and deposit rules to the draft dev.ucp.lodging.booking capability merged in September 2026, ahead of Google's planned hotel booking in AI Mode.
- An ecommerce team that sells through both ChatGPT and Google keeps an ACP integration for ChatGPT checkout and a UCP profile at /.well-known/ucp for Google surfaces, both fed from one product catalog.
