Universal Commerce Protocol (UCP) by Google
What is the Universal Commerce Protocol?#
The Universal Commerce Protocol (UCP) is Google's open standard for enabling AI agents to discover, browse, and complete transactions in online stores. Developed in collaboration with Shopify and other major e-commerce platforms, UCP provides a structured way for AI shopping agents to understand product catalogs, check inventory, add items to carts, and process payments — all without human intervention. UCP is designed for the emerging world where consumers say 'buy me running shoes under $100' to an AI assistant and the agent handles the entire shopping journey. For merchants, implementing UCP means your store is accessible to this new generation of AI-powered shoppers. The protocol uses a well-known endpoint (/.well-known/ucp.json) for agent discovery and defines standard schemas for products, carts, and checkout flows.
UCP Manifest Structure#
The UCP manifest declares your store's commerce capabilities to AI agents. It includes your store's identity, supported payment methods, API endpoints for browsing and purchasing, and the product catalog format. Below is an example of a UCP manifest.
{
"schema_version": "1.0",
"store": {
"name": "Example Store",
"url": "https://store.example.com",
"description": "Premium outdoor gear and apparel",
"currency": "USD",
"shipping_regions": ["US", "CA", "GB", "EU"]
},
"capabilities": {
"browse_products": true,
"search_products": true,
"view_inventory": true,
"add_to_cart": true,
"checkout": true,
"order_tracking": true
},
"endpoints": {
"products": "/api/ucp/products",
"search": "/api/ucp/search",
"cart": "/api/ucp/cart",
"checkout": "/api/ucp/checkout"
},
"authentication": {
"type": "oauth2",
"authorization_url": "/oauth/authorize",
"token_url": "/oauth/token"
}
}UCP vs ACP: Choosing the Right Protocol#
UCP and ACP serve similar goals but come from different ecosystems. UCP is Google's standard, designed to work seamlessly with Google Shopping, Google AI, and the broader Google ecosystem. ACP (Agentic Commerce Protocol) is from Stripe and OpenAI, optimized for Stripe's payment infrastructure and OpenAI's agent framework. For maximum coverage, implement both. They are not mutually exclusive and serve different agent populations. UCP tends to be more catalog-focused (browse, search, discover), while ACP is more transaction-focused (payment intents, checkout completion). If you must choose one, consider where your customers' AI interactions originate: Google ecosystem users will encounter UCP-compatible agents, while ChatGPT and Stripe-integrated agents will use ACP.
For maximum AI commerce coverage, implement both UCP and ACP. They serve different agent populations and are not mutually exclusive.
Frequently Asked Questions
No. UCP is designed to be implementable by stores of any size. If you have a Shopify store, UCP support is being integrated directly into the platform. For custom stores, the manifest is a simple JSON file.
No. UCP is payment-processor agnostic. It supports OAuth2 for authentication and can work with any payment gateway. Unlike ACP which is Stripe-native, UCP works with Stripe, PayPal, Square, or any other processor.
Google AI agents are already beginning to use UCP in limited testing. As Google Shopping integrates AI more deeply throughout 2026, UCP adoption will accelerate. Early implementation positions you ahead of competitors.