UCP, the Universal Commerce Protocol, is an open-source standard from Google that gives AI agents one shared way to shop across merchants — discovering products, building a cart, checking out, and handling fulfilment and order updates. Instead of an agent integrating separately with every store's checkout, UCP defines common primitives a merchant exposes once and any compliant agent can use, the way HTTP standardised the web.
As of its January 2026 specification, UCP standardises six functional primitives: product discovery, checkout, discount handling, fulfilment, order management, and identity linking. It is compatible with AP2 for the payment-authorisation step, and merchants can implement it via ordinary APIs, the Agent2Agent (A2A) protocol, or the Model Context Protocol. That makes UCP the commerce-orchestration counterpart to the Agentic Commerce Protocol (ACP) from OpenAI and Stripe — the two are parallel bets at the same layer, sitting above the payment protocols beneath them.
Google announced UCP on 11 January 2026, co-developed with retailers including Shopify, Etsy, Wayfair, Target, and Walmart and endorsed by more than 20 partners such as Visa, Mastercard, Stripe, and American Express. Its first product is the Universal Cart, a single cart shoppers fill across Google surfaces — Search and the Gemini app first, with YouTube and Gmail to follow — where the brand stays the merchant of record. So UCP is genuinely an open standard, while its largest early deployment is Google's own surfaces; both are true. Partners, surfaces, and rollout geography are dated to mid-2026 and will move.