UCP vs ACP: the protocols powering AI shopping
The Agentic Commerce Protocol (ACP), released by OpenAI and Stripe in September 2025, standardises how an AI agent and a merchant complete a checkout, including product feeds and delegated payment; it powers purchases inside ChatGPT. The Universal Commerce Protocol (UCP), from Google, Shopify and partners, covers the wider shopping journey from discovery and basket to checkout, orders and post-purchase. They overlap but often work together with Google’s Agent Payments Protocol (AP2) for payment authorisation and MCP for connecting agents to tools.
Why do AI shopping protocols matter?
In agentic commerce, an AI agent searches, compares and, with permission, buys on a customer’s behalf. For that to work across thousands of stores, agents and merchants need shared rules for product information, baskets, checkout and payment. Several open standards have appeared since late 2025 to provide them. Our overview of what agentic commerce is covers the bigger picture.
| ACP | UCP | |
|---|---|---|
| Full name | Agentic Commerce Protocol | Universal Commerce Protocol |
| Backed by | OpenAI and Stripe | Google, Shopify and partners |
| Main focus | Agent checkout and delegated payment | The full journey: discovery, basket, checkout, orders, post-purchase |
| Where you see it | Purchases inside ChatGPT | Google’s AI shopping experiences and partner agents |
| How merchants adopt it | Through Stripe or supported commerce platforms | Through Shopify and other supporting platforms |
Details change as the standards develop; check each specification and your platform’s documentation for current support.
What does ACP do?
ACP defines how an agent reads a merchant’s product feed, creates a checkout and passes payment in a secure, delegated way, while the merchant stays the seller of record and handles fulfilment. OpenAI and Stripe released it under an open licence in September 2025, and it underpins buying directly within ChatGPT. Merchants typically connect through Stripe or a commerce platform that supports it, rather than implementing the protocol from scratch.
What does UCP do?
UCP aims to cover the whole shopping journey, not only checkout. It describes how agents discover products and offers, build and change baskets, complete purchases, track orders and handle returns, using common building blocks across merchants. Google and Shopify are among its backers, which makes it relevant to Google’s AI shopping features and to the large number of Shopify stores. See Google AI Mode shopping and Shopify agentic storefronts.
How do AP2 and MCP fit in?
Google announced the Agent Payments Protocol (AP2) in September 2025 to create signed mandates showing what a customer authorised, and later moved it under the FIDO Alliance. The Model Context Protocol is the general standard for connecting agents to tools, including product search and order systems.
Do UCP and ACP compete?
For most merchants, the practical question is not which protocol to choose but whether their commerce platform and payment provider support the agents customers use.
What should merchants do now?
- Clean your product data: Complete titles, descriptions, attributes, images, prices and stock.
- Publish clear policies: Delivery times, returns and warranties in structured, readable form.
- Check your platform: See which agent channels Shopify, WooCommerce or your platform supports.
- Talk to your payment provider: Confirm support for agent payments and fraud controls.
- Track agent orders: Tag orders by channel so you can see agent-driven sales.
- Keep the site strong: Many customers still check the brand site before approving.
Our guide to product page optimisation for humans and AI agents covers the content side.
What does this mean for the shopper?
For customers, the protocols are invisible. They ask an assistant to find something, review a short list, approve a purchase and receive confirmation, often without visiting a website. Good experiences depend on accurate information, clear prices including delivery, transparent return policies and easy ways to change or cancel orders. Merchants that make those details clear and reliable will be the ones agents recommend and customers trust.
What risks should merchants consider?
- Less control over how products are presented inside agents
- New fraud patterns and chargeback questions
- Dependence on platform support and fees
- Thinner direct relationships with customers
- Standards still evolving, so plan for change
How UIUX Studio helps
The standards will keep evolving, but the fundamentals will not: accurate product data, clear policies and a trustworthy store are what agents and customers rely on, whichever protocol carries the order.
We help merchants prepare product data, storefronts and integrations for AI agents. Talk to our product engineering and Agentic AI & Automation teams.
Frequently asked questions
What is ACP?
The Agentic Commerce Protocol from OpenAI and Stripe for agent checkout and delegated payment.
What is UCP?
The Universal Commerce Protocol from Google, Shopify and partners covering the full shopping journey.
Do I need to implement them myself?
Usually not; platforms and payment providers handle most of the work.
Do UCP and ACP compete?
They overlap on checkout but differ in scope; platforms may support both.
What should I do first?
Clean product data and check your platform’s agent features.