Frequently Asked Questions

Find answers to common questions about the Universal Commerce Protocol (UCP).

General

What is the Universal Commerce Protocol (UCP)?

UCP is our new open standard designed to unify digital commerce. We built it to enable direct, instant purchases across AI surfaces like AI Mode in Google Search and the Gemini app. Our goal is to reduce friction in the buying process and help you minimize cart abandonment.

What are the main benefits of integrating with UCP?

When you integrate with UCP, you gain:

  • Expanded reach: access to users directly on our surfaces, including AI Mode in Google Search and the Gemini app.
  • Reduced checkout friction: we enable direct purchases within the interaction flow, keeping users engaged.
  • Control: you remain the Merchant of Record, maintaining full control over your customer relationships and data.
  • Flexibility: we offer different integration paths (Native and Embedded) to suit your brand and technical stack.
  • Readiness for agentic experiences: we are designing this to support upcoming agentic capabilities, such as multi-item carts and account linking.

What makes UCP different?

  • Modular and extensible: UCP is designed to be modular and extensible to support rich commerce experiences using capabilities and extensions.
  • Fast and easy to implement: UCP allows merchants the choice to select the set of capabilities and extensions they want to support and the communication medium that best suits their development needs such as APIs, MCP, or A2A.
  • Co-designed with industry leaders: UCP is open source and is designed directly by a collaboration of industry leaders, to support the diverse needs of a rich commerce ecosystem.
  • Secure and seamless payments: UCP supports secure payments using tokenization and allows merchants to build on existing payment integrations using payment handlers.

What surfaces will our integrations appear on?

At launch, your UCP integration will power experiences on AI Mode in Google Search, as well as both the Gemini web application and the Gemini mobile app. We are planning support for other surfaces in the future.

Integration & Configuration

Is UCP compatible with my existing tech stack?

We built UCP on open standards, making it seamlessly compatible with major existing protocols you might already use, such as AP2, A2A, and MCP.

Do I need to make changes to my Merchant Center account?

Merchant Center remains central to our ecosystem. You must ensure your product feeds, brand assets, return policies, and business contact information are complete and up-to-date there. We provide specific data requirements in our Implementation Guides.

How are we different from other protocols?

We designed UCP as a comprehensive open standard specifically for AI-driven commerce, co-developed with industry partners. Unlike protocols focused solely on payments, we support the broader shopping journey (including discovery and consideration) powered by our Shopping Graph.

How do I distinguish traffic from UCP versus my own channels?

You can differentiate UCP traffic from your regular website or app traffic in two ways:

  • HTTP Headers: You can identify incoming UCP requests at the network level by verifying that the request meets two conditions: a header with the label UCP-Agent:Profile is present, and the User-Agent value begins with Google/UCP.
  • API Contracts: We exchange checkout, order, and transaction lifecycle events using the API contracts established in our specifications. This lets you clearly differentiate traffic and payments flowing through our AI surfaces at the application level.

How do we handle real-time inventory checks?

As the Merchant of Record, it is your responsibility to perform real-time inventory checks. If an item is out of stock at any point during the checkout process, your API must return a response message that includes the out_of_stock error code. When your system returns this error, we show a relevant error message to the user, such as, "This item is currently out of stock. Try another option or check back later."

For more information, see the out_of_stock error examples.

How can I safely migrate my live integration to a newer UCP specification version?

To ensure safe testing and deployment, we recommend setting up a separate API endpoint for the new specification version. This approach provides better traffic isolation and allows Google to securely manage and monitor the traffic transition between the two endpoints. If any issues arise during the migration, Google can route traffic back to your original endpoint.

Does Google automatically validate and block international shipping addresses?

No. As the Merchant of Record, it is your responsibility to validate shipping addresses. When a user selects a shipping address, we pass the destination details (including the address_country code) to your server during the Create Checkout or Update Checkout API calls. If the address is outside your supported shipping zones, your system must send this in the API response using standard UCP error codes, such as address_undeliverable or address_unverifiable.

For more information, see Error Codes.

Payments & Tokenization

How does UCP relate to the Agent Payments Protocol (AP2)?

AP2 is our standard for secure, agent-led payment transactions. We use UCP to orchestrate the broader purchase lifecycle, while AP2 can be used as a specialized payment layer within UCP. This is particularly useful for future scenarios involving autonomous AI agent transactions.

How do we process payments? Do I need to support Google Pay?

You don't need to support checkout with Google Pay API on your website or app, but your Payment Service Provider (PSP) must be able to process our tokens. Most major global PSPs support Google Pay.

If I have multiple Google Pay & Wallet console accounts (e.g., one per country), which should I specify in my UCP profile?

We don't require you to use different profiles for different countries. You have the flexibility to use whichever Google Pay & Wallet console account—or combination of accounts—that best suits your business setup.

If I already have Google Pay, will you respect my existing configuration (e.g., card restrictions)?

Because UCP is a separate integration, you must explicitly provide your Google Pay configuration within your UCP profile. You can use the same configuration parameters that you use for your website or app, or you can provide a different configuration. Keep the following requirements in mind:

  • Supported parameters: The settings are similar to your existing integration, but the supported parameters aren't a one-to-one match (for example, UCP uses snake_case instead of camelCase). For a complete list, see the Google Pay payment handler configuration.
  • Supported authentication methods: UCP on Google's AI surfaces only supports PAN_ONLY for the allowed_auth_methods field. You can include other methods (such as CRYPTOGRAM_3DS), but they aren't used during the UCP checkout flow.

Security & Monitoring

How does Google monitor my API endpoint health?

Google may periodically send HTTP requests to your API endpoints to ensure they are available and responsive. These health check requests will include a specific User-Agent header: User-Agent: Google-UCP-Prober/1.0.

How can I verify that API requests are genuinely coming from Google?

To verify that requests originate from Google, follow the official guidance at Verifying Requests from Google. This guide details methods such as reverse DNS lookups and provides links to our published IP range files.

Can I restrict incoming Google API requests to specific countries (georestriction)?

No. Google manages outbound traffic dynamically using core servers, so we cannot guarantee that requests will originate from a specific country. Instead of using geographic IP blocking, we recommend configuring your firewall to authenticate and allow Google's requests based on the OAuth 2.0 Bearer token or other secure signatures provided during the machine-to-machine authentication process.

User Experience

Will Native integration affect my product ranking?

No. Opting for our Native integration does not influence how we rank your offers in product listings. The user experience for listings remains consistent; however, offers integrated with UCP will feature the direct purchase option.

Can users change their shipping address during checkout?

Yes. We allow users to review and change their shipping address during the flow. We expect your system to dynamically update shipping costs and taxes based on the new address provided.

How do I signal that optional user authentication (Identity Linking) is available?

To signal that optional authentication is available, you must declare the Identity Linking capability in your UCP profile. This allows Google's surfaces to discover the capability before a checkout session is initiated.

For more information, see Identity Linking - OAuth 2.0.

How are recoverable checkout errors displayed to the user?

When your API returns a recoverable error—such as address_undeliverable—our UI prompts the user to update their information (for example, by selecting a different shipping address). Ensure you accurately set the severity as recoverable in your messages array; otherwise, the user encounters a blocking error screen and cannot complete the checkout.

For more information, see Error Codes.

Will I lose control of my customer data?

No. You are the Merchant of Record. You retain full ownership of your customer relationships and data.

How do we handle customer privacy?

Our standard security and privacy practices apply to the interaction, but you own the transaction data. We are also building features like account linking that are designed to keep the user in control of their data.

What Terms & Conditions apply to a UCP transaction?

Your Terms & Conditions cover the purchase, just as if the customer checked out on your own website. We display these terms to the customer, and they must accept them during the checkout flow.

Are there limitations on re-marketing to customers acquired through UCP?

Since you are the Merchant of Record, you possess the customer's information just as you would for a direct purchase. Standard privacy regulations and consent practices apply. We are planning a feature that will allow users to explicitly opt-in to marketing communications during checkout in a future update.

What is the data retention policy for order data passed to Google?

Google retains standard order data (the information that appears on the user's "My orders" page) indefinitely until the user explicitly requests to have it deleted, in accordance with our standard data deletion policies.

Because you are the Merchant of Record, your own company's data retention and compliance policies (for example, holding financial records for 7 years) continue to apply to the data stored on your systems.