Agentic Commerce Protocol vs Universal Commerce Protocol: What’s the Difference

ACP vs UCP explained: what each protocol does, how they differ, and what AI shopping means for your ecommerce store.

September 11, 2026
by chhavi

ACP is an open standard from OpenAI and Stripe. It lets AI agents, buyers and merchants talk to each other during a purchase, including checkout and payment. The Universal Commerce Protocol (UCP) is a broader open standard developed with Google and Shopify that standardises commerce capabilities across the wider journey, from product discovery and cart creation to checkout, payments and post-purchase activity.

The two protocols solve a similar problem, but they approach it from different architectural starting points.

Table of Content

What is the Agentic Commerce Protocol?

The agentic commerce protocol was introduced by OpenAI and Stripe in September 2025 alongside Instant Checkout in ChatGPT. Its purpose is to give AI agents and merchants a common way to exchange the information needed to complete a transaction while allowing the merchant to remain the merchant of record and continue using its existing commerce and payment infrastructure.

In practical terms, ACP creates a bridge between three parties:

The buyer, who authorises the purchase.
The AI agent, which handles the conversational shopping experience.
The merchant, which controls the order, fulfilment, returns and customer relationship.

A merchant exposes an ACP-compatible checkout. The agent can create and update a checkout session, receive the authoritative cart and pricing information, and submit the purchase for completion.

The protocol has also evolved beyond its original September 2025 release. As of 17 April 2026, the official ACP repository lists this as the latest stable specification. (Agentic Commerce Protocol (ACP))

How Does the ACP Stripe Integration Work?

The payment layer is where the ACP Stripe integration becomes particularly important.

With Stripe’s implementation, the customer’s payment credentials are not simply handed to the AI agent. Instead, Stripe uses a Shared Payment Token (SPT).

The basic flow is:

The buyer chooses a payment method during the agent-led checkout.
Stripe creates an SPT representing the payment credential.
The token is restricted by conditions such as the merchant, transaction amount and expiry.
The agent passes the token to the merchant through the ACP flow.
The merchant uses its payment infrastructure to complete the transaction.

This means the agent can help orchestrate the purchase without receiving the customer’s underlying payment credentials. Stripe describes the token as a controlled credential that can be passed between the buyer, agent and business, while the merchant’s payment provider handles the actual payment.

ACP also defines a delegate payment mechanism. In the current specification, a payment handler can require delegation, with the delegated credential constrained by an allowance such as maximum amount, currency, expiry and checkout session.

That distinction matters. ACP is not simply an API for putting a “Buy” button inside ChatGPT. It establishes a controlled interaction between the agent and merchant while separating payment credentials from the agent’s broader application logic.

What is the Universal Commerce Protocol?

Google and Shopify launched the Universal Commerce Protocol (UCP) in January 2026 as an open standard for interoperability among commerce platforms, AI agents, businesses, payment providers, and other participants.

UCP covers a wider part of the buying journey than ACP, from product discovery to post-purchase.

Instead of concentrating primarily on the transaction and checkout interaction, it defines reusable capabilities and extensions that can cover different parts of the customer journey.

Current UCP capabilities include areas such as:

Product catalogue and discovery
Cart
Checkout
Fulfilment
Orders
Identity linking
Payments
Extensions such as discounts and loyalty

The protocol is also designed to work across different transports, including REST, MCP and A2A. As of 25 August 2026, the official UCP documentation lists this as its latest specification version. (Universal Commerce Protocol)

This makes UCP less about a single checkout implementation and more about creating a common language through which different commerce systems can discover capabilities and negotiate how a transaction should work.

What Is the Difference Between ACP and UCP?

The easiest way to understand agentic commerce protocol vs UCP is to look at their scope.

Area	Agentic Commerce Protocol (ACP)	Universal Commerce Protocol (UCP)
Origin	OpenAI + Stripe	Google + Shopify
Core purpose	Connect AI agents, buyers and businesses to complete purchases	Standardise interoperability across commerce participants and workflows
Commerce scope	Strong focus on agent-led checkout and transaction flows	Broader journey from discovery through post-purchase
Checkout	Core part of the protocol	Core capability within a larger capability model
Payments	Delegated payments and payment handlers are central to ACP	Payment handlers support different payment and credential providers
Product discovery	Supported through evolving specifications	Explicit catalogue and discovery capabilities
Cart	Supported in current ACP versions	Dedicated cart capability
Orders	Supported	Dedicated order capability
Transport	HTTP/API-oriented, with MCP support in current releases	REST, MCP, A2A and embedded approaches
Architecture	Interaction and checkout-focused	Capability-based and extensible
Current specification	17 April 2026 stable release	25 August 2026 specification

The important point is that UCP is broader, not simply “ACP with a different name.”

UCP is designed around capability discovery and negotiation. A business can advertise what it supports, while an agent can determine which capabilities and payment handlers are available for a particular transaction.

ACP, meanwhile, emerged from a more focused problem: enabling an AI agent such as ChatGPT to conduct a purchase while merchants retain their existing systems and payment relationships.

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Is UCP replacing ACP?

No. UCP is not replacing ACP. Both are active, open standards, and their developers continue to update them. They overlap on checkout, payments, agents and merchants, but their scopes are different.

UCP explicitly builds on or works alongside other protocols, including Agent Payments Protocol (AP2), Agent2Agent (A2A) and Model Context Protocol (MCP). Its payment model is deliberately extensible, with payment handlers allowing different providers to define how their credentials and payment methods work.

ACP is also evolving through payment handlers, extensions, authentication, cart, feed and MCP-related capabilities. Its current repository continues to describe OpenAI and Stripe implementations as reference implementations.

The better question for ecommerce teams is not which protocol won. It is which agentic commerce interfaces your business needs to support.

How will ACP impact your ecommerce business?

AI shopping changes the point at which an ecommerce website can lose or win a customer.

Previously, the journey often looked like:

Search → Product page → Cart → Checkout → Payment

With agentic commerce, the journey can begin inside an AI interface. The agent may discover products, compare options, construct a cart and then communicate with the merchant’s systems to complete the purchase.

That makes technical readiness increasingly important.

First, product data needs to be structured and accurate. In addition, pricing, availability, shipping, returns, and product attributes need to be machine-readable. Similarly, checkout endpoints need to provide predictable behaviour. Finally, authentication and payment flows need to have clear boundaries.

For ecommerce teams, this means agentic commerce is not only a payments project. It is also a data, architecture and discoverability project.

The agentic commerce protocol and UCP represent two important approaches to solving that problem. Understanding their differences now gives merchants a clearer view of how AI-driven buying may connect with their existing ecommerce infrastructure.

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FAQ's

Agentic Commerce Protocol: Your Questions, Answered

Everything you need to know about the Agentic Commerce Protocol, from how it works to what it means for the future of commerce.

The Agentic Commerce Protocol is an open standard co-developed by OpenAI and Stripe for communication between AI agents, buyers and businesses during commerce transactions. It provides standardised mechanisms for agent-led checkout and payment while allowing merchants to retain control of fulfilment, customer relationships and their existing commerce infrastructure.

The Universal Commerce Protocol is an open standard developed with Google and Shopify to allow commerce platforms, agents and businesses to interoperate through common capabilities. Its scope covers areas including discovery, catalogue, cart, checkout, fulfilment, orders and payments.

ACP began with a strong focus on agent-led checkout and secure payment delegation, while UCP provides a broader capability-based framework covering more of the commerce journey. They overlap, but they are not identical protocols.

Stripe can issue a Shared Payment Token that represents the buyer’s payment credential without exposing the underlying payment details to the AI agent. The token is scoped with controls such as merchant and transaction limits, then passed through the commerce flow so the merchant can process payment through its payment infrastructure.

No. ACP is an open standard rather than a protocol limited to one consumer interface. OpenAI’s initial implementation powers Instant Checkout in ChatGPT, while the ACP project provides specifications that other agents and developers can implement.

The answer depends on which AI commerce surfaces and integrations a business wants to support. Rather than treating either protocol as a replacement for the ecommerce platform, businesses should assess how well their product data, catalogue, checkout, payment, fulfilment and order systems can expose structured capabilities to AI agents.

The agentic commerce protocol is part of a much larger shift: the ecommerce interface is moving from pages that people navigate towards systems that both people and AI agents can interact with. For merchants, the opportunity is not simply to appear in an AI answer. It is to make the underlying commerce infrastructure ready when that answer becomes a purchase.

In short, ACP and UCP both make your store readable to AI agents. Start by cleaning up product data, checkout endpoints and payment flows so agents can use them.