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The open-source standard launched by Google in January 2026 enabling AI agents to discover and interact with merchants across the full shopping lifecycle.
Co-developed with Shopify and backed by 20+ global partners including Walmart, Target, Visa, and Mastercard.
As announced by Google at the National Retail Federation (NRF) conference in January 2026, the Universal Commerce Protocol (UCP) is an open-source standard that enables AI agents to discover merchants and interact across the full shopping lifecycle, from product discovery and consideration through cart management, checkout, payment processing, post-purchase support, and loyalty programs.
Co-developed with Shopify and backed by 20+ global partners including Walmart, Target, Etsy, Wayfair, Visa, Mastercard, Stripe, Adyen, American Express, Best Buy, Flipkart, Macy's, The Home Depot, and Zalando, UCP represents the industry's commitment to open, decentralized AI commerce.
According to the UCP specification, merchants publish a /.well-known/ucp manifest on their domain, similar to robots.txt, enabling decentralized discovery without requiring approval from any central authority. AI agents can access this manifest to understand merchant capabilities and begin interactions via REST APIs, Model Context Protocol (MCP), or Agent-to-Agent (A2A) communication.
Merchants publish /.well-known/ucp manifests on their domains. No approval process or centralized directory required. Discovery works like robots.txt.
UCP supports REST APIs, Model Context Protocol (MCP) for deep AI integration, and Agent-to-Agent (A2A) communication for direct agent interaction.
From discovery to loyalty programs, UCP covers every stage: product search, consideration, cart management, checkout, payments, post-purchase support, and rewards.
Payment processing via AP2 (Agent Payments Protocol) with Google Pay and planned PayPal support. Merchants remain Merchant of Record.
Works across Google Search AI Mode, Gemini app, and any third-party AI agent. Not locked to a single platform or payment provider.
Available on GitHub and at ucp.dev with full documentation, specifications, and community contributions.
A merchant publishes a /.well-known/ucp manifest file on their domain (e.g., example.com/.well-known/ucp). This manifest describes their capabilities, supported protocols (REST, MCP, A2A), and API endpoints for the full shopping lifecycle.
AI agents discover the manifest by accessing the /.well-known/ucp endpoint on any merchant domain. No approval process or centralized directory is required. Discovery is decentralized and open, similar to how search engines discover robots.txt files.
The AI agent and merchant negotiate capabilities dynamically based on what the merchant supports (product search, cart APIs, checkout, loyalty programs) and what the agent needs. This ensures compatibility and optimal interaction.
The agent interacts with the merchant via REST APIs, Model Context Protocol (MCP), or Agent-to-Agent (A2A) protocols across the entire shopping lifecycle: discovery, consideration, cart management, checkout, post-purchase support, and loyalty programs.
Payment is processed via AP2 (Agent Payments Protocol) with Google Pay as the primary payment method (PayPal support is planned). The merchant remains the Merchant of Record, maintaining the customer relationship and retaining control over customer data.
As announced at NRF 2026, UCP is backed by Google and Shopify along with 20+ global partners representing major retailers, payment providers, and e-commerce platforms:
Note: UCP's decentralized discovery model means any merchant can implement UCP without requiring approval from these partners. The /.well-known/ucp manifest enables open participation in the ecosystem.
UCP and Agentic Commerce Protocol (ACP), launched by OpenAI and Stripe in October 2025, represent two different approaches to AI commerce. Here's a quick comparison:
| Feature | UCP (Google) | ACP (OpenAI) |
|---|---|---|
| Launch Date | January 2026 (NRF) | October 2025 |
| Backers | Google, Shopify, 20+ partners | OpenAI, Stripe |
| Discovery Model | Decentralized (/.well-known/ucp) | Centralized (OpenAI approval) |
| Protocol Support | REST, MCP, A2A | REST only |
| Lifecycle Coverage | Full lifecycle (discovery to loyalty) | Primarily checkout-focused |
| Payment | AP2 with Google Pay (PayPal planned) | Stripe Instant Checkout |
| Merchant Relationship | Merchant of Record | Merchant of Record |
| Surface Support | Surface-agnostic (any AI agent) | ChatGPT-coupled |
Key Insight: ACP processes approximately 50 million daily shopping queries on ChatGPT, with 36% of shopping query users completing purchases through the platform. This demonstrates significant consumer adoption of AI-powered commerce, though it's currently limited to the ChatGPT ecosystem.
Read the full UCP vs ACP comparisonDecentralized discovery means AI agents can discover UCP-compatible merchants by accessing the /.well-known/ucp manifest on any merchant's domain, similar to how search engines discover robots.txt files. No central authority or approval process is required.
Model Context Protocol (MCP) is a deep integration protocol that allows AI models to interact more naturally with merchant systems beyond traditional REST APIs. It enables richer context sharing and more sophisticated agent-merchant interactions.
Agent-to-Agent (A2A) communication enables direct interaction between AI agents and merchant systems without requiring traditional API calls. This allows for more dynamic, conversational commerce interactions.
In UCP, the merchant remains the Merchant of Record, meaning they maintain the direct customer relationship, control customer data, and handle post-purchase support. This protects merchant brand relationships and customer privacy.
Yes. According to the UCP specification, merchants can implement UCP on top of existing e-commerce platforms like Shopify, WooCommerce, Magento, and custom solutions. Shopify co-developed UCP, making it easier for Shopify merchants to adopt.
UCP is open source and available on GitHub. Full documentation, specifications, and implementation guides are available at ucp.dev. You can also explore our detailed guide to Google's UCP.
Browse the UCP directory to discover verified merchants implementing the Universal Commerce Protocol.