The Agentic Commerce Protocol (ACP) is an open technical standard, co-developed by OpenAI and Stripe and announced on September 29, 2025, that lets AI agents complete purchases on behalf of users while the merchant stays in control of the sale. ACP defines a common set of messages exchanged by three parties (the buyer and their AI agent, the AI platform such as ChatGPT, and the merchant), so a shopper can discover a product inside a chat and pay for it without leaving the conversation [1][2]. It is the standard behind ChatGPT's "Instant Checkout" feature, is published under the Apache 2.0 open-source license with OpenAI and Stripe as founding maintainers, and is one of several competing standards in the emerging field of agentic commerce [2][3][4]. It is distinct from Google's Agent Payments Protocol (AP2), which addresses payment authorization rather than checkout [13].

Fact	Detail
Full name	Agentic Commerce Protocol (ACP)
Developers / maintainers	OpenAI and Stripe (founding maintainers)
Announced	September 29, 2025
License	Apache 2.0 (open source)
Repository	github.com/agentic-commerce-protocol
Core specs	Agentic Checkout Spec; Delegated Payment Spec; product feed
Payment primitive	Shared Payment Token (SPT), scoped to one merchant and cart
Merchant of record	The merchant (not OpenAI or Stripe)
First platform	ChatGPT Instant Checkout (United States)
First merchants	US Etsy sellers (Sept 29, 2025); Shopify merchants to follow
Notable later adopters	Salesforce (Sept 2025), PayPal (Oct 28, 2025), Walmart, and others
MCP support	Added in the April 17, 2026 spec release
Main rivals	Google AP2 and UCP; Amazon's closed stack; Perplexity

What is the Agentic Commerce Protocol?

ACP describes itself, in its public repository, as "an interaction model and open standard for connecting buyers, their AI agents, and businesses to complete purchases seamlessly" [4]. Stripe frames it as "a new open standard codeveloped by Stripe and OpenAI that enables programmatic commerce flows between buyers, AI agents, and businesses" [3]. The motivation is that as AI assistants move from answering questions to taking actions, buyers want to finish a purchase inside the assistant, and merchants want to reach those buyers without rebuilding their checkout for every AI app. ACP lets a merchant integrate once and then accept orders from any ACP-compatible agent.

OpenAI and Stripe announced ACP on September 29, 2025, alongside Instant Checkout in ChatGPT, and open-sourced the specification under Apache 2.0 [1][2][3]. The launch was presented by Fidji Simo, OpenAI's CEO of Applications, and Will Gaybrick, Stripe's President of Technology and Business [2]. The two companies act as founding maintainers and have said they intend to move the project toward broader community governance, and eventually neutral foundation stewardship, as the ecosystem matures. The specification has been revised several times since launch. Its published changelog records an initial release on September 29, 2025, fulfillment enhancements on December 12, 2025, capability negotiation on January 16, 2026, extensions, discounts and payment handlers on January 30, 2026, and a cart, feed, orders, authentication and Model Context Protocol update on April 17, 2026 [4].

How does ACP work?

ACP keeps a clean separation between the agent that talks to the buyer and the merchant that fulfills the order. It has two main parts.

The Agentic Checkout Spec defines REST endpoints that a merchant exposes so an agent can create, update, and complete a checkout session. When a ChatGPT user is ready to buy, ChatGPT calls these endpoints. The merchant validates the cart, calculates shipping and sales tax, runs its own fraud and risk checks on its own stack, and returns the full checkout state with every response. Webhooks notify the agent of order events such as shipment.

The Delegated Payment Spec governs money movement. Rather than handing the merchant a raw card number, the agent tokenizes the buyer's chosen payment credential and "delegates" it to the merchant under strict constraints, an allowance that fixes a maximum amount and an expiry [5]. In OpenAI and Stripe's implementation this token is the Shared Payment Token (SPT), a single-use credential that Stripe created so an application like ChatGPT can initiate a payment without exposing the buyer's card details [7]. The token is scoped to a single merchant and cart total and cannot be reused outside the approved purchase. Stripe's Shared Payment Token is the first Delegated Payment Spec-compatible implementation, with additional payment service providers (PSPs) intended to follow [5][7].

Crucially, the merchant remains the merchant of record. In Stripe's words, "With ACP, you maintain your customer relationships as the merchant of record, retaining control over which products can be sold, how they're presented, how transactions are processed, and how orders are fulfilled" [3]. The merchant, not OpenAI or Stripe, charges the card through its own payment service provider, owns the customer relationship, decides which products can be sold and how they are displayed, and chooses whether to accept or decline each order based on its own risk signals [2][3]. ACP is deliberately payment-provider neutral. A business already on Stripe can enable agentic payments in as little as one line of code, while a business on another processor can implement the open spec with its existing infrastructure [2]. The protocol covers physical and digital goods, subscriptions, and asynchronous "buy for me" purchases, and it supports both single-item and multi-item carts. ACP is built on familiar web primitives (large language model agents calling ordinary REST APIs over HTTPS), which is part of why merchants can adopt it without a bespoke integration for each AI platform.

What is Instant Checkout in ChatGPT?

Instant Checkout is OpenAI's first ACP product and the reason the protocol exists in practice. Announced on September 29, 2025, it lets ChatGPT users in the United States buy a recommended product inside the chat, and it is available to free, Plus, and Pro users [1]. When a shopper asks for a recommendation and decides to buy, a Stripe-powered checkout appears inline, the buyer confirms with a saved payment method, and the order is placed with the merchant. OpenAI has reported that ChatGPT reaches roughly 700 million weekly users, a large potential funnel for participating merchants [10].

At launch the feature handled single-item purchases from US-based Etsy sellers, with support for more than a million Shopify merchants (named examples included Glossier, Vuori, Spanx, and SKIMS) described as coming soon [1]. OpenAI later expanded the experience to multi-item carts and additional retailers, and connected it to generative AI product recommendations in the chat [9].

The early rollout struggled, and the difficulties were documented widely in March 2026 by CNBC, Retail Dive, and Search Engine Land [10][11][12]. Merchant onboarding was slow, and the first version of the experience forced each recommended product into its own separate transaction, shipment, and delivery, which shoppers disliked. Walmart, which had made about 200,000 products available through Instant Checkout starting in November 2025, said the in-chat checkout converted roughly three times worse than sending shoppers to Walmart.com. Walmart executive Daniel Danker disclosed the figure at a Morgan Stanley conference on March 4, 2026, and called the experience "unsatisfying" [12]. In response, OpenAI began shifting away from in-chat checkout toward retailer "apps" inside ChatGPT that hand the shopper off to the retailer's own site to pay, using ACP mainly for product discovery. Walmart relaunched inside ChatGPT through an app powered by its own Sparky shopping agent, and reporting indicated that the redesigned, retailer-controlled experience recovered conversion to roughly 70 percent of Walmart.com's rate [11][12]. According to CNBC, retailers that integrated ACP for discovery include Target, Sephora, Nordstrom, Lowe's, Best Buy, The Home Depot, and Wayfair [10].

Who has adopted ACP?

Reported participants and milestones, attributed to the sources below, include:

Etsy: the first live merchants, US-based sellers, from September 29, 2025 [1].
Shopify: more than a million merchants slated to follow, with named brands including Glossier, Vuori, Spanx, and SKIMS [1].
Salesforce: announced support for ACP in collaboration with Stripe on September 29, 2025, extending the protocol to Commerce Cloud merchants [18].
PayPal: announced on October 28, 2025 that it would adopt ACP to power Instant Checkout in ChatGPT, connecting its global merchant network and roughly 400 million active accounts and handling merchant routing and payments behind the scenes [19].
Walmart: listed about 200,000 products from November 2025, then wound down direct Instant Checkout in early 2026 in favor of a Sparky-powered app [10][11].
Others: Instacart and DoorDash were also reported as testing or integrating the approach [10].

Actual adoption in the first months was narrower than the headline merchant counts suggested. CNBC reported only a few dozen Shopify merchants live early on, reflecting the onboarding friction that OpenAI and its partners then worked to reduce [10].

How does ACP compare to Google's AP2?

ACP is frequently confused with Google's AP2, but the two sit at different layers and are best understood as complementary rather than as direct substitutes.

ACP (OpenAI and Stripe) is a commerce-and-checkout protocol. It standardizes the messages for building a cart, completing a checkout session, and delegating a payment token to a merchant who remains the merchant of record. Its center of gravity is the merchant integration and the buying experience inside an agent.

AP2 (Agent Payments Protocol), announced by Google on September 16, 2025 with a coalition of more than 60 firms including Mastercard, American Express, PayPal, Coinbase, and Adyen, is a payment-authorization and trust protocol [13][14]. Its core idea is the mandate, a cryptographically signed statement that proves a user authorized an agent to spend within defined limits. AP2 defines three signed mandates, Intent, Cart, and Payment, carried as W3C Verifiable Credentials, and is payment-method agnostic across cards, real-time payments, and digital assets [13][14]. It is designed as an extension of Google's Agent2Agent (A2A) protocol and the Model Context Protocol.

The simplest way to keep them apart: ACP describes how a checkout happens, while AP2 describes how a payment is authorized and proven. Google's closest counterpart to ACP on the commerce side is its separate Universal Commerce Protocol (UCP), which Google designed to compose with AP2, with UCP shaping the checkout session and AP2 supplying the cryptographic mandate [15]. Because ACP is neutral about the underlying payment method, ACP and AP2 can in principle interoperate.

The table below summarizes the layering.

Protocol	Owner(s)	Announced	What it standardizes
ACP	OpenAI + Stripe	Sept 29, 2025	Cart, checkout session, delegated payment token
AP2	Google + 60+ partners	Sept 16, 2025	Payment authorization via signed mandates (W3C VCs)
UCP	Google	2025	Commerce/checkout session (composes with AP2)
MCP	Anthropic	Nov 2024	Connecting agents to tools and data (not payments)
x402	Coinbase	2025	HTTP 402 stablecoin micropayments

Both ACP and AP2 are distinct from the Model Context Protocol (MCP), the open standard for connecting AI models to external tools and data. MCP is about giving an agent context and capabilities, not moving money. ACP added MCP support in its April 17, 2026 release so that commerce can be exposed to agents as MCP tools [4]. Another adjacent effort is Coinbase's x402, which uses the HTTP 402 "Payment Required" status code for programmatic stablecoin payments. Industry analysts generally frame ACP, AP2, UCP, and x402 as layers of an emerging agentic-commerce stack rather than as winner-take-all rivals [17].

Why does the Agentic Commerce Protocol matter?

ACP marked one of the first times a major AI platform put a working purchase flow directly inside a chatbot used by hundreds of millions of people, and it set a template that competitors matched quickly. Within weeks Google had countered with AP2, and later UCP [13][15]. Amazon kept building a closed stack around its Rufus assistant (used by an estimated 250 million customers) and its "Buy for Me" feature, which it began piloting in April 2025; in November 2025 Amazon sued Perplexity over its Comet shopping agent [16]. On March 9, 2026, US District Judge Maxine M. Chesney granted Amazon a preliminary injunction barring Comet from accessing Amazon's password-protected systems, finding Amazon likely to succeed on claims under the Computer Fraud and Abuse Act; the 9th Circuit Court of Appeals then issued an administrative stay around March 16, 2026 that paused the order before it took effect, leaving the appeal unresolved [16]. The contest is now less about whether agents will shop and more about who controls the checkout, the customer relationship, and the resulting data.

The early Instant Checkout results also tempered expectations. The Walmart conversion data and OpenAI's pivot toward discovery-plus-handoff apps suggested that, at least through early 2026, many shoppers were not yet comfortable completing entire purchases inside a chat, and that the hardest problems were merchant onboarding, cart and fulfillment logic, and trust rather than the payment plumbing [10][12]. As an open, Apache 2.0 standard with a published spec and reference implementations from both OpenAI and Stripe, ACP's longer-term importance may lie less in any single feature than in whether it becomes shared infrastructure that many agents and merchants adopt, the way earlier web and payment standards eventually did.

References

OpenAI, "Buy it in ChatGPT: Instant Checkout and the Agentic Commerce Protocol." https://openai.com/index/buy-it-in-chatgpt/
Stripe Newsroom, "Stripe powers Instant Checkout in ChatGPT and releases Agentic Commerce Protocol codeveloped with OpenAI" (September 29, 2025). https://stripe.com/newsroom/news/stripe-openai-instant-checkout
Stripe, "Developing an open standard for agentic commerce." https://stripe.com/blog/developing-an-open-standard-for-agentic-commerce
Agentic Commerce Protocol, GitHub repository and README. https://github.com/agentic-commerce-protocol/agentic-commerce-protocol
OpenAI Developers, "Agentic Commerce Protocol" and Delegated Payment Spec. https://developers.openai.com/commerce/specs/payment
Agentic Commerce Protocol specification site. https://www.agenticcommerce.dev/
Stripe Documentation, "Shared payment tokens." https://docs.stripe.com/agentic-commerce/concepts/shared-payment-tokens
Digital Commerce 360, "OpenAI expands agentic commerce push" (February 16, 2026). https://www.digitalcommerce360.com/2026/02/16/openai-expands-agentic-commerce-push/
Digital Commerce 360, "OpenAI reveals updates to its agentic commerce experience for ChatGPT" (March 24, 2026). https://www.digitalcommerce360.com/2026/03/24/openai-agentic-commerce-updates-chatgpt-walmart/
CNBC, "OpenAI's first try at agentic shopping stumbled. It's trying again" (March 20, 2026). https://www.cnbc.com/2026/03/20/open-ai-agentic-shopping-etsy-shopify-walmart-amazon.html
Retail Dive, "Walmart brings Sparky to ChatGPT as OpenAI rethinks Instant Checkout." https://www.retaildive.com/news/walmart-sparky-chatgpt-instant-checkout/815647/
Search Engine Land, "Walmart: ChatGPT checkout converted 3x worse than website." https://searchengineland.com/walmart-chatgpt-checkout-converted-worse-472071
Google Cloud Blog, "Announcing Agent Payments Protocol (AP2)" (September 16, 2025). https://cloud.google.com/blog/products/ai-machine-learning/announcing-agents-to-payments-ap2-protocol
TechCrunch, "Google launches new protocol for agent-driven purchases" (September 16, 2025). https://techcrunch.com/2025/09/16/google-launches-new-protocol-for-agent-driven-purchases/
Google Developers Blog, "Under the Hood: Universal Commerce Protocol (UCP)." https://developers.googleblog.com/under-the-hood-universal-commerce-protocol-ucp/
CNBC, "Amazon wins court order to block Perplexity's AI shopping agent" (March 10, 2026). https://www.cnbc.com/2026/03/10/amazon-wins-court-order-to-block-perplexitys-ai-shopping-agent.html
Orium, "Agentic Payments Explained: ACP, AP2, and x402." https://orium.com/blog/agentic-payments-acp-ap2-x402
Salesforce Investor Relations, "Salesforce Announces Support for Agentic Commerce Protocol in Collaboration with Stripe" (September 29, 2025). https://investor.salesforce.com/news/news-details/2025/Salesforce-Announces-Support-for-Agentic-Commerce-Protocol-in-Collaboration-with-Stripe/default.aspx
PayPal Newsroom, "OpenAI and PayPal Team Up to Power Instant Checkout and Agentic Commerce in ChatGPT" (October 28, 2025). https://newsroom.paypal-corp.com/2025-10-28-OpenAI-and-PayPal-Team-Up-to-Power-Instant-Checkout-and-Agentic-Commerce-in-ChatGPT

Editing: Agentic Commerce Protocol