Universal Commerce Protocol (UCP)

The Universal Commerce Protocol is an open-source standard developed by Google and Shopify that enables AI agents to handle the full commerce journey -- from product discovery to checkout to post-purchase -- across any compatible platform.

UCP was announced by Google CEO Sundar Pichai at the National Retail Federation (NRF) conference on January 11, 2026. It is the most ambitious agentic commerce protocol to date, covering not just checkout (like ACP) but the entire lifecycle: discovery, browsing, cart management, payment, order tracking, returns, and customer service.

The protocol defines interactions between four actors: Platforms (AI agents and applications), Merchants, Credential Providers (identity verification), and Payment Service Providers. A critical design principle: the merchant remains the Merchant of Record for all transactions. Merchants retain full ownership of customer relationships, data, and the post-purchase experience (Google Developers, Jan 2026).

UCP was co-developed with Shopify and is endorsed by over 20 major partners including Stripe, Visa, Mastercard, Adyen, American Express, Best Buy, Macy's, Home Depot, Target, Walmart, Wayfair, Etsy, and Zalando (Google Blog, Jan 2026).

UCP matters because it standardizes AI commerce across the full shopping journey -- not just one piece of it. While ACP handles checkout and MCP handles data connectivity, UCP is designed to be the end-to-end framework.

Google's Shopping Graph already indexes over 50 billion product listings, with 2 billion updated every hour (Google, Jan 2026). UCP provides the standardized interface for AI agents to interact with this massive product database and complete transactions on behalf of consumers.

The protocol is designed for interoperability. UCP works with Agent Payments Protocol (AP2) for secure payment handling, Agent-to-Agent protocol (A2A) for cross-agent coordination, and MCP for structured data access. Merchants can integrate via REST APIs, A2A, or MCP bindings -- whichever fits their existing infrastructure (Google Developers, Jan 2026).

Early UCP participants include Wayfair, Chewy, Etsy, and Quince on Google's AI Mode agentic checkout (Google, Feb 2026). As Google's AI Mode reaches hundreds of millions of Search users, UCP-compliant merchants will have direct access to this traffic.

UCP is modular and extensible. Merchants implement capabilities based on what their systems support:

Discovery. Merchants publish product catalogs through a /.well-known/ucp discovery endpoint -- a standardized URL where AI agents can find and access the merchant's product data. This is similar to how robots.txt tells search crawlers what to index.

Browsing and Selection. AI agents query the merchant's catalog, filter by consumer preferences, and present options. UCP supports rich product attributes including images, variants, availability, pricing tiers, and shipping options.

Cart and Checkout. The agent manages cart operations (add, remove, update quantities) and initiates checkout. Payment is handled through AP2-compatible payment service providers. The consumer's payment credentials are never exposed to the AI agent.

Post-Purchase. UCP includes capabilities for order tracking, returns initiation, and customer service routing. This full lifecycle coverage differentiates UCP from checkout-only protocols.

Shopify Engineering described the co-development process: "We co-developed UCP with Google to create an open standard for AI agents to connect and transact with any merchant" (Shopify Engineering, Jan 2026).

The three protocols are complementary. A retailer might use MCP to make their catalog data accessible, ACP to power ChatGPT Instant Checkout, and UCP to enable Google AI Mode transactions. Infrastructure platforms like Paz.ai handle multi-protocol compliance so merchants implement once and reach all channels.

• UCP is the first protocol to cover the entire commerce journey -- discovery through post-purchase
• Launched at NRF 2026 by Google and co-developed with Shopify, endorsed by 20+ major partners
• Merchants retain full ownership as Merchant of Record -- UCP does not disintermediate the retailer
• UCP is interoperable with ACP, MCP, AP2, and A2A
• The /.well-known/ucp discovery endpoint is the standardized way merchants expose their catalogs to AI agents