Which Agentic Commerce Protocol Should Your Store Run? UCP or ACP?

ChatGPT dropped in-chat checkout in March 2026, so UCP and ACP now do different jobs. UCP lets shoppers buy from you in Google AI Mode, Gemini, and Copilot. ACP gets you found in ChatGPT. Here is which one your store needs.

You probably need both, but they now do different jobs. UCP lets shoppers buy from you inside Google AI Mode, Gemini, and Microsoft Copilot. ACP gets your products shown in ChatGPT, and the sale then happens on your own site.

That split is new. In March 2026, OpenAI shut down Instant Checkout, the in-chat buying feature ACP was built for. If you read a UCP vs ACP comparison from 2025, its fee math and its advice are out of date.

What changed in 2026?

ChatGPT stopped selling and started recommending. On March 24, 2026, OpenAI refocused shopping in ChatGPT on product discovery and sent checkout back to merchants' own sites. OpenAI said the first version of Instant Checkout "did not offer the level of flexibility that we aspire to provide."

Buying inside the chat did not convert. Walmart told WIRED in March 2026 that purchases inside ChatGPT converted at about one third the rate of clicks through to Walmart.com.

Google went the other way. In March, UCP added carts, live catalog data, and account linking for loyalty perks. At Google Marketing Live on May 20, Google said UCP checkout would roll out in AI Mode and Gemini across the US over the summer. YouTube and Gmail come next, then Canada, Australia, and the UK.

A timeline of 2026 agentic commerce events: UCP launch in January, Instant Checkout retired in March, UCP checkout rollout announced in May, 17,767 UCP stores in September, TikTok Buy Direct on UCP in October

What is UCP?

UCP, the Universal Commerce Protocol, lets an AI agent buy from your store on a shopper's behalf. Google and Shopify launched it on January 11, 2026, with Etsy, Wayfair, Target, and Walmart as co-developers.

UCP covers the whole purchase. The agent searches your catalog, fills a cart, checks out, and tracks the order. Your store publishes a small file at /.well-known/ucp that tells agents what it supports.

The UCP Checker tracker counted 17,767 verified stores on September 22, 2026. Shopify (10,632) and Wix (6,929) make up 98% of them. Our UCP guide covers the protocol in depth.

What does ACP do now?

ACP, the Agentic Commerce Protocol, now gets your products into ChatGPT's shopping results. OpenAI and Stripe launched it in September 2025 to power Instant Checkout.

Today ACP mainly carries your product feed: titles, prices, stock, and images. ChatGPT uses that feed to show and compare products. When a shopper picks one, ChatGPT opens your checkout in an in-app browser or a new tab.

Target, Sephora, Nordstrom, Lowe's, Best Buy, The Home Depot, and Wayfair send their feeds to ChatGPT this way. Walmart went further and built its own app inside ChatGPT, with account linking and Walmart payments.

ACP still has checkout features. Its latest release, from January 30, 2026, added payment handlers and a way for agents and stores to agree on supported features. But ChatGPT no longer offers in-chat checkout. I would not spend developer time on ACP checkout until OpenAI says where it will be used.

UCP vs ACP at a glance

Google UCPOpenAI ACPMade byGoogle and ShopifyOpenAI and StripeLive sinceJanuary 2026September 2025What it does for youAgents buy from youChatGPT shows your productsWhere shoppers find youAI Mode, Gemini, CopilotChatGPTWhere the sale happensInside the AI appOn your siteProtocol feeNoneNone since March 2026What you set upA file at /.well-known/ucpA product feedVerified stores17,767 (Sept 2026)Not published

What does each one cost you?

Neither protocol charges you a fee. You pay your normal card processing cost, the same as for any online order. On a $100 order at Stripe's standard 2.9% plus $0.30, you keep $96.80 either way.

That is a big change from 2025. Instant Checkout added a 4% OpenAI fee on top of processing, so a $100 ChatGPT sale cost you about $7.20. That fee ended with Instant Checkout.

The real cost now is your product data. Both channels show wrong prices or sold-out items if your feed is stale. Shopify says product data sent through its catalog converts twice as well in AI chats as data that agents scrape from your pages.

Which one do you need?

Your platform decides most of the answer.

A decision flow: Shopify stores likely have both and should check eligibility; Wix stores have UCP and should add a ChatGPT feed; other platforms should send an ACP feed first and then add UCP; stores with no online checkout can skip both

You sell on Shopify

You likely have both already. Shopify's Agentic Storefronts are on by default for eligible US stores. They send your products to ChatGPT. For eligible brands, they also turn on UCP checkout in Google AI Mode, Gemini, and Copilot.

Make sure your store meets Shopify's rules:

Your store is based in the US and sells to US customers.
Your products are eligible for Shopify Catalog.
Your store policies are published.
Your checkout does not force shoppers to log in.

You sell on Wix

UCP is likely on already. Wix turned it on across its stores and started adding cart support on September 22, 2026. For ChatGPT, you still need a product feed. Check whether your Wix plan offers a ChatGPT sales channel.

You use another platform or a custom store

Start with ACP, because it is now the smaller job. You send OpenAI a product feed and keep your own checkout. There is nothing new to build at checkout.

Then add UCP. Ask your platform first: BigCommerce, WooCommerce, Magento, and Shopware stores already show up in UCP Checker's data, and Salesforce Commerce Cloud support was due in October 2026. Google is also making UCP setup simpler in Merchant Center.

You do not sell online

Skip both. Spend the time on what AI agents read before they recommend you, such as crawler access and structured data. Our agent readiness stack shows where to start.

What should you watch next?

UCP keeps spreading to new apps. TikTok launched Buy Direct on October 5, 2026, built on UCP. It lets people buy from the For You feed and is in testing with eligible advertisers. The next UCP release is due in December 2026 or January 2027.

ChatGPT is the bigger open question. OpenAI could bring checkout back in a new form, or leave it to retailer apps like Walmart's. Until it decides, treat ChatGPT as a place to be found, and Google as a place to sell.

GenReady checks for your /.well-known/ucp file on every scan. It also checks that ChatGPT's crawlers, OAI-SearchBot and ChatGPT-User, can reach your pages.

Want to know if AI shopping agents can find and buy from your store? Run a free GenReady scan. It takes under 60 seconds.