This guide provides detailed instructions for developers integrating with the
Universal Commerce Protocol (UCP) on Google. It covers the necessary steps to
enable transactions directly on Google's AI surfaces (Search, Gemini).

This guide provides detailed instructions for developers integrating with the
Universal Commerce Protocol (UCP) on Google. It covers the necessary steps to
enable transactions directly on Google's AI surfaces (Search, Gemini). Because
[UCP](https://ucp.dev/) is an evolving standard, not all features
defined in the spec are available on Google's surfaces. Refer to the detailed
guides within this site for the most up-to-date information on feature support.

> [!IMPORTANT]
> **Important:** This guide is for merchants who don't have access to the UCP integration hub in Google Merchant Center. If you have access to the hub in your account, follow the [UCP integration in Merchant
> Center](https://developers.google.com/merchant/ucp/guides/merchant-center/integration) path instead.

## Implementation at a glance

Follow these steps to go live on Google AI surfaces. You can choose to integrate
a checkout path (to support purchases directly on Google) or a cart path (to
receive shopping carts and hand off to your website).

1. [Prepare your Merchant Center
   account](https://developers.google.com/merchant/ucp/guides/overview/merchant-center). Configure shipping, returns, and your product feed.
   - Once you're ready, [join the waitlist](https://support.google.com/merchants/contact/ucp_integration_interest) to get in contact with Google for UCP implementation. Your integration must be approved by Google before you can go live on AI Mode in Google Search and Gemini.
2. [Prepare your UCP profile](https://developers.google.com/merchant/ucp/guides/overview/ucp-profile). This allows Google to negotiate services and capabilities and discover your payment handlers and public keys for signature verification.
3. [Authentication](https://developers.google.com/merchant/ucp/guides/overview/authentication). Secure your API endpoints.
4. Choose your core implementation path:
   - **Native checkout path:** implement the [Native checkout overview](https://developers.google.com/merchant/ucp/guides/overview/native-checkout) to handle full purchases directly on Google AI surfaces. This path also requires you to:
     - [Google Pay payment handler](https://developers.google.com/pay/api/universal-commerce-protocol/google-pay-payment-handler) to allow users to submit payments.
     - [Order lifecycle (post-purchase)](https://developers.google.com/merchant/ucp/guides/overview/order-lifecycle) to push order updates.
   - **Cart path:** implement the [Cart API](https://developers.google.com/merchant/ucp/guides/overview/cart-overview) to transfer a user's shopping cart from Google surfaces to your website.
5. (Optional) Add extended capabilities:
   - [Identity Linking - OAuth
     2.0](https://developers.google.com/merchant/ucp/guides/overview/identity-linking): implement OAuth 2.0 to sync user profiles (replaces the default guest checkout).
   - [Promo codes and discounts
     overview](https://developers.google.com/merchant/ucp/guides/overview/promo-codes): allow users to apply promotions during checkout.