Google UCP

Google Universal Commerce Protocol (UCP) - Overview

Google's Universal Commerce Protocol (UCP) is a new open-source standard for "agentic" commerce that unifies the end‑to‑end shopping process across devices and platformsdevelopers.googleblog.comdevelopers.google.com. In practice, UCP defines a common API and data schema so that AI assistants and other surfaces (e.g. Google Search's AI Mode, Gemini) can interact with any merchant's backend. UCP works with existing infrastructure and complementary protocols (Agent Payments AP2, Agent2Agent A2A, Model Context Protocol)developers.googleblog.comblog.google. It was co-developed by Google with industry partners (Shopify, Etsy, Wayfair, Target, Walmart, etc.) and is designed to collapse the usual N×N integration complexity into a single point of integrationdevelopers.googleblog.comblog.google.

Key features: UCP standardizes the shopping flow - from product discovery through checkout and order management - via REST or JSON-RPC APIsdevelopers.googleblog.comdevelopers.google.com. It provides capabilities schemas (e.g. checkout, fulfillment, discounts) and supports payment handlers like Google Pay. It is modular and extensible (new agentic capabilities can be added), interoperable with existing payment and agent protocols, and security‑first (tokenized payments and verifiable user consent)developers.googleblog.comdevelopers.google.com. For example, a merchant's UCP profile can advertise supported capabilities and payment methods (a JSON at /.well-known/ucp with version, endpoints, and public keys)developers.google.com.

Benefits for merchants: UCP lets e-commerce sites reach shoppers on AI platforms while retaining full control of branding, customer data and checkout experiencedevelopers.google.comdevelopers.googleblog.com. Merchants remain the "Merchant of Record" and handle fulfillment, even though Google (or another platform) renders the shopping UI. In practice, UCP unlocks "instant buy" experiences (e.g. buy buttons in Google Search/Gemini) that reduce cart abandonment. Sites adopting UCP can use their existing Merchant Center feed for product listings, then enable direct checkout with UCP (keeping customer relationships and data)developers.google.comblog.google. In summary, UCP simplifies integration (one API for all agentic surfaces), expands reach (access to new AI-driven channels), and builds shopper confidence (secure, transparent payment flows and preserved merchant policies)developers.google.comblog.google.

Implementation Guide for a Basic HTML/JS Site

To integrate UCP on your site, follow these steps:

1. Merchant Center & Product Feed: Obtain a Google Merchant Center account and ensure your products are uploaded (free listings). In your product data, set the native_commerce attribute to TRUE for any item you want to sell via UCPdevelopers.google.com. Also configure your global return policies and customer support info in Merchant Center, since these are shown during checkoutdevelopers.google.comdevelopers.google.com. (These settings satisfy legal and user‑experience requirements for UCP checkouts.)
2. Publish Your Business Profile: Host a JSON document at https:///.well-known/ucp describing your UCP endpoints and capabilitiesdevelopers.google.com. Example fields include the UCP version, service endpoint URLs, and supported capabilities (like dev.ucp.shopping.checkout, fulfillment, etc.)developers.google.com. Also list payment handlers (e.g. a Google Pay handler entry) and any OAuth signing keys. Google (and other agents) will fetch this profile to learn how to communicate with your backend.
3. Implement Checkout REST APIs: Build the required UCP REST endpoints on your server. At minimum, implement:
4. (Optional) Embedded Checkout: By default UCP's Native integration lets Google render the UI for entering shipping/payment. If your checkout flow is complex or needs custom branding, you can instead supply an Embedded option: host a checkout page on your site and give its URL to Google, which will iframe it into the UCP flowdevelopers.google.com. In that case, implement a UCP endpoint that returns your iframe URL. (Native checkout is simpler to start with; embedded is only needed for highly bespoke flows.)
5. Payment Integration (JS SDK): If you offer Google Pay, include Google's JavaScript library in your site (e.g. ) and configure it as a UCP payment handlerdevelopers.google.com. In your business profile JSON, include a com.google.pay handler entry with your Google Pay merchant ID, allowed card networks, etc.developers.google.com. When Google calls your /checkout-sessions endpoint, respond with a payment.handlers array that includes an entry with "id":"gpay", "name":"com.google.pay", and your serialized Google Pay API configdevelopers.google.comdevelopers.google.com. Google will then initiate the Google Pay UI in its checkout. (UCP is payment‑method agnostic, so you can also implement other handlers like PayPal or your own tokenization.)
6. Account Linking (Optional): To support returning customers (loyalty, saved addresses, etc.), implement UCP's Identity Linking via OAuth2. You'd host OAuth2 endpoints (/oauth2/authorize, /oauth2/token) and a discovery doc at /.well-known/oauth-authorization-serverdevelopers.google.com. This lets Google authenticate users on your site (Google Streamlined Linking) without breaking flow. If you skip this, UCP will use guest checkout by defaultdevelopers.google.com.
7. Site Markup (Structured Data): Ensure your HTML product pages use [schema.org/Product] JSON‑LD with accurate name, description, images, price, currency, availability, and brand. In particular, include an offers block with pricing and currency to match your Merchant Center feed. (Google also expects you to list your merchant return policy; you can embed a hasMerchantReturnPolicy schema in offers or just rely on the Merchant Center return policy you configured.) Proper structured data isn't strictly part of UCP's protocol but helps Google verify your product info and prevents listing errors.
8. Order Lifecycle (Webhooks): After checkout completion, you should update order status via UCP or Google's APIs so the user can track shipments. For a basic integration, call Google's [Order Management webhooks] when orders ship or are refunded. (See UCP docs for the Order and Fulfillment capabilities.)

By following these steps, your site will support UCP: customers can discover your products via Google's AI interfaces, add them to a UCP session, and complete purchase securely via your API. All integration details above are documented in Google's UCP guidesdevelopers.google.comdevelopers.google.com.

Sources: Official Google documentation and blog posts on UCPdevelopers.googleblog.comdevelopers.google.comdevelopers.google.comdevelopers.google.com. These detail UCP's design goals, API endpoints, and setup requirements.

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