Catalog Optimization
What Is the Agentic Commerce Protocol (ACP)? What Brands Need to Know Now
ACP is the open standard from OpenAI and Stripe behind ChatGPT shopping: what it specifies, what changed with Instant Checkout, what brands should do.
Sakshi Gupta
The Agentic Commerce Protocol (ACP) is an open standard, developed by OpenAI and Stripe, that gives a shopper's AI agent a shared way to read a merchant's products and start a checkout. It launched on September 29, 2025 alongside Instant Checkout in ChatGPT. The merchant stays the merchant of record and keeps control of orders.
What is the Agentic Commerce Protocol?
ACP describes how three parties talk to each other: the buyer, the buyer's AI agent (ChatGPT, in the first implementation), and the business selling the product. The official site calls it an open standard for programmatic commerce flows between buyers, AI agents and businesses, released under the Apache 2.0 license (agenticcommerce.dev).
The goal is one integration that works across AI agents, instead of a custom build for each one. Stripe describes it the same way: a merchant integrates once and can sell through agents, while choosing what it sells, how the brand appears and how orders are fulfilled (Stripe newsroom, Sept 29, 2025).
ACP is also not tied to Stripe as a payment processor. Businesses on other payment providers can adopt it with the providers they already use.
Who built ACP, and when?
OpenAI and Stripe co-developed it and announced it on September 29, 2025. Today the two companies are the Founding Maintainers listed in the project's GitHub repository, which says they govern it jointly by consensus and that the long-term aim is neutral foundation stewardship. The spec is still labeled beta (ACP on GitHub).
The spec uses date-based versions. The first was 2025-09-29. As of today the latest stable version in the repository is 2026-04-17, which added cart, feed, orders, authentication and MCP support. Earlier releases added fulfillment changes, capability negotiation, extensions, discounts and payment handlers.
What does ACP actually specify?
Three flows matter to a merchant, according to OpenAI's developer documentation (OpenAI commerce docs).
Flow | What it covers | Who builds it |
|---|---|---|
Product feed | Structured product data (identifiers, pricing, inventory, media, fulfillment options), shared so ChatGPT can show products accurately. Starts with a sample, then daily snapshots. | Merchant, or the platform hosting the store |
Checkout | Five REST endpoints that create, update, retrieve, complete and cancel a checkout session (Agentic Checkout Spec). The merchant validates the order, calculates tax and accepts or declines it. | Merchant |
Delegated payment | A way to pass the buyer's payment credential to the agent without exposing it. Stripe's Shared Payment Token is the first compatible implementation, limited to one merchant and one basket total. | Payment provider |
Notice what sits in the first row. Before an agent can sell anything, it has to read the product correctly. A feed with missing identifiers, vague titles or stale availability fails at the first step, long before checkout.
Nudge Catalog Enrichment works on that step. Its Catalog Analysis scans every product and scores it for how readable it is to AI, and its Agentic Protocol Integration structures the catalog to fit ACP and UCP so agents can recommend and check out natively.
What happened to ChatGPT Instant Checkout?
Instant Checkout is where many articles about ACP are out of date. At launch, US ChatGPT users could buy from US Etsy merchants inside the chat, with Shopify merchants listed as coming soon (Stripe).
In March 2026 the direction changed. OpenAI said it was letting merchants use their own checkout experiences while it focused on product discovery, and that Instant Checkout was moving to Apps. It described ACP as the infrastructure connecting users to merchants across the shopping journey (CNBC, Mar 24, 2026; Digital Commerce 360, Mar 6, 2026).
In practice, ChatGPT now works mostly as a discovery layer. Merchants share feeds and promotions through ACP so products are represented in ChatGPT, and retailers such as Target, Sephora and Nordstrom support the new discovery experience. Walmart and Target run their own apps inside ChatGPT for deeper experiences.
The takeaway: ACP did not disappear. The part that shoppers noticed, a native buy button in the chat, is no longer the center of it. The product data layer is.
Does Shopify support ACP and ChatGPT?
Yes, through Shopify's own system. Shopify Agentic Storefronts is active by default for eligible stores, and products reach AI channels through Shopify Catalog. For ChatGPT, Shopify describes the channel as discovery-focused: shoppers buy on the merchant's own online store checkout, opened in ChatGPT's in-app browser or a new tab on the web (Shopify Help Center).
Stores need to accept Shopify's Agentic Storefronts Supplemental Terms. Brands not on Shopify can use Shopify's Agentic plan, which opens Shopify Catalog to them (Shopify newsroom, Jan 11, 2026).
That means a Shopify brand does not build ACP endpoints by hand to appear in ChatGPT. But the data Shopify passes along is the data in your catalog. If your attributes are thin, the channel carries the thin version.
You can see how your catalog reads today with the free catalog scan.
ACP vs UCP: how do they differ?
UCP is the Universal Commerce Protocol, co-developed by Shopify and Google and endorsed at launch by 20+ retailers and platforms. It is an open standard for AI agents to transact with any merchant, works with any payment processor and supports REST, MCP, AP2 and A2A (Shopify newsroom). Here is the short version. For the full side-by-side, read our ACP and UCP comparison.
Option | What it is | Built by | Where shoppers meet it | What a brand does |
|---|---|---|---|---|
Nudge (not a protocol) | Platform that prepares the catalog for both protocols and tracks whether the brand is recommended | Nudge | Across ChatGPT, Gemini, Perplexity and Google AI surfaces | Connect the store, review scored fixes, approve changes |
ACP | Open standard for feeds, checkout and delegated payment | OpenAI and Stripe | ChatGPT | Share a product feed, implement checkout endpoints if going deeper |
UCP | Open standard for agents to transact with any merchant | Shopify and Google | Google AI Mode, Gemini and other agent surfaces | Keep Shopify Catalog or Merchant Center data accurate |
The two protocols overlap more than they compete. The shared requirement is the same: accurate, structured product data that an agent can read without guessing.
What does a merchant need to implement ACP?
For a full integration, OpenAI's documentation lists a product feed, checkout endpoints and a payment provider that supports the delegated payment spec. OpenAI is not the merchant of record, so the actual checkout state and payment processing stay on your systems. Stripe adds that merchants must accept or decline each order and handle tax, fulfillment and returns.
Feed onboarding in ChatGPT is, per OpenAI's Get Started guide, currently available to approved partners, delivered by SFTP, with a full snapshot recommended at least once a day (OpenAI Get Started). The guide also bars some product categories, including adult content, age-restricted goods and weapons.
Nudge sits upstream of all of this. It does not replace your payment provider or become your merchant of record, and it is not a checkout processor. It makes the catalog readable, and it counts native agent checkouts separately from humans who arrive through a link.
What should a DTC brand do now?
Skip the question of whether to build ACP endpoints this quarter. Work through this order instead.
Check whether ChatGPT recommends you at all. Nudge AI Visibility runs a tracked set of topics and prompts against ChatGPT, Gemini, Perplexity and Google AI, and records whether your brand was mentioned, which competitors were, and which sources the answer used. Branded and unbranded prompts are tagged separately, because strong branded results say little about category demand.
Fix the product data agents read. Title clarity, attributes, variants, availability and Product schema. See our guides on product schema mistakes and optimizing PDPs for AI search. Catalog Enrichment writes Shopify taxonomy categories and category metafields in bulk, behind a preview and an approval step.
Confirm your channel setup. On Shopify, check Agentic Storefronts eligibility in the admin. Off Shopify, look at the Agentic plan or a direct feed.
Plan for the click. When ChatGPT sends a shopper to your checkout, the page they land on decides the sale. Nudge Funnels builds journeys matched to where the visit came from, and runs each against the default page as a control.
Read your agent traffic. Nudge Agent Analytics classifies the requests agents make to your store (crawl, citation fetch, training pull) and breaks them down by page. None of it shows in GA4. Totals run from the date tracking went live.
If you want to see how this applies to your catalog, book a demo.
For background on the category, see our explainer on what agentic commerce is.
Frequently asked questions
What does ACP stand for?
ACP stands for Agentic Commerce Protocol. It is an open standard developed by OpenAI and Stripe, announced on September 29, 2025, that lets a shopper's AI agent read a merchant's products and start a checkout. It is not the same as other uses of the acronym.
Is ChatGPT Instant Checkout still available?
OpenAI said in March 2026 that Instant Checkout was moving to Apps and that merchants could use their own checkout while it focused on discovery. Check OpenAI's current documentation before planning around a native buy button. ChatGPT shopping itself continues.
Do I need to build ACP endpoints to sell in ChatGPT?
Not necessarily. Shopify merchants reach ChatGPT through Shopify Catalog and Agentic Storefronts, where shoppers finish on the merchant's own checkout. Custom builds apply to brands that want deeper native integrations or run their own stack.
Does ACP only work with Stripe?
No. Stripe's Shared Payment Token is the first compatible payment implementation, but the delegated payment spec is open, and merchants on other processors can adopt ACP with their existing providers.
Is ACP the same as Google's UCP?
No. UCP is a separate open standard co-developed by Shopify and Google. The two address similar problems for different AI surfaces, and both depend on clean structured product data.
