Google has released the first update to its Universal Commerce Protocol (UCP) for AI-driven shopping across partner retailers. In a new Shopping product blog post, the company updated the Universal Commerce Protocol with draft Cart and Catalog capabilities, highlighted Identity Linking, and outlined simplified onboarding through Merchant Center. The changes are documented in Google's Shopping product blog and in the latest UCP specifications.
Key details: Google Universal Commerce Protocol update
Cart and Catalog are available as draft specifications in the UCP project, while Identity Linking appears in the latest stable specification. Google states that all three capabilities are optional for retailers.
- The Cart specification lets agents add and save multiple items in a basket from a single store, according to the Cart UCP spec.
- Cart supports pre-purchase sessions that can convert into checkout sessions when shoppers decide to buy.
- The Catalog Catalog spec enables agents to retrieve real-time product data, including variants, prices, and stock availability.
- Catalog supports both product search and direct product lookups using identifiers.
- Identity Linking connects shopper accounts to UCP platforms using OAuth 2.0 authorization flows and is documented in the stable Identity Linking UCP spec at launch.
- According to Google, Identity Linking lets loyalty prices, discounts, and shipping benefits carry across supported AI shopping surfaces.
- Google highlights Identity Linking for shoppers buying through AI Mode in Search or the Gemini app rather than the retailer's own site.
Merchant Center onboarding and platform partners
Google is simplifying Universal Commerce Protocol onboarding through Merchant Center. The company described the new process as designed for "more retailers of all sizes" over the coming months. Merchant Center documentation currently lists the checkout feature as limited to selected merchants that complete an interest form.
According to Google's Merchant Center help page, only products with the native_commerce attribute show the checkout button in eligible listings. Retailers manage these settings inside Merchant Center to align product data with UCP checkout support.
Google named Commerce Inc, Salesforce, and Stripe as platform partners planning Universal Commerce Protocol implementations. Each partner announced its own integration plans, according to Google. The company said these implementations will arrive "in the near future," with additional partners expected to follow.
Background and official specifications
Google first introduced the Universal Commerce Protocol at the National Retail Federation conference in January. This is the first public update to UCP since that launch. Universal Commerce Protocol specifications are published openly at ucp.dev, with draft and stable versions separated.
Cart and Catalog are both marked as draft specifications in the UCP repository. Identity Linking is listed in the latest stable specification and was available at launch. The UCP open-source project is hosted on GitHub, where community contributors can review and comment on proposals.
Google stated that it plans to bring UCP capabilities to AI Mode in Search and the Gemini app. The company has not shared a specific launch timeline beyond describing Merchant Center onboarding as arriving in the "coming months".
Inside Google's Universal Commerce Protocol that lets AI agents tap carts, catalogs and loyalty pricing
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