# ACP (Agentic Commerce Protocol): what it is and how it works > What the ACP (Agentic Commerce Protocol) from OpenAI and Stripe is, what happened to Instant Checkout in 2026 and what data a store needs to appear in ChatGPT. URL: https://clione.ai/glossary/acp/ Lang: en ACP stands for plenty of things. Here it is the Agentic Commerce Protocol, the way ChatGPT receives products from stores and, in some cases, processes the purchase. People search it by its full name more than by the acronym, and rightly so: it is **how a merchant's catalog reaches ChatGPT's shopping answers**. A store cares because it decides which data to provide and in what format. ## How it works The ACP is an open standard for purchase flows between buyers, [AI agents](/glossary/ai-agent/) and merchants, developed by Stripe and OpenAI under the Apache 2.0 license. It supports physical goods, digital goods, subscriptions and asynchronous purchases, offers REST endpoints and endpoints compatible with the [MCP (Model Context Protocol)](/glossary/mcp/), and **keeps the merchant as the seller** (the _merchant of record_).[^acp-site] In OpenAI's documentation, the store sees three pieces:[^openai-acp-concepts] - **The [product feed](/glossary/product-feed/).** The merchant shares its product data with OpenAI, field by field, so ChatGPT can show it accurately in search and shopping. - **The checkout session.** It is displayed inside ChatGPT, but the order state and the charge happen in the merchant's own systems, and the merchant accepts or rejects each order. - **The [delegated payment](/glossary/delegated-payments/).** OpenAI securely passes the payment details to the merchant or its payment provider. OpenAI is not the seller: the merchant uses its own provider, as with any other digital payment. The specification is published on GitHub with date-based versions. The first is from September 29, 2025; later came improvements to shipping, capability negotiation, extensions and discounts, and the current stable version, from April 17, 2026, adds cart, feed, orders, authentication and a link to MCP. OpenAI and Stripe are the founding maintainers, major changes go through formal proposals, and **the repository labels the project as beta**.[^acp-repo] ## What has happened since 2025 OpenAI launched the ACP on September 29, 2025 alongside [Instant Checkout](/glossary/instant-checkout/): ChatGPT users in the United States could buy from US Etsy sellers without leaving the chat, one item at a time, with more than a million Shopify merchants announced as coming next. The merchant paid a small fee per completed purchase, and OpenAI said product results were organic and that offering Instant Checkout did not earn preference, although it counted as one more factor when ranking merchants that sell the same product.[^openai-buy] On March 24, 2026 the focus shifted. OpenAI extended the ACP to product discovery: merchants share feeds and promotions, directly or through providers such as Salesforce and Stripe, and chains such as Target, Sephora, Nordstrom, Lowe's, Best Buy, The Home Depot and Wayfair were already integrated. Shopify stores arrive through [Shopify Catalog](/glossary/shopify-catalog/) with no extra work. And OpenAI acknowledged that the first version of Instant Checkout did not give it the flexibility it wanted, so it **lets merchants use their own checkout process** while it concentrates on discovery.[^openai-discovery] Instant Checkout has not disappeared: the developer documentation says it is available to approved partners,[^openai-acp-concepts] and the help center says ChatGPT may offer it for some eligible products and merchants.[^openai-shopping-help] Stripe, for its part, presents the ACP as one of the two protocols for selling through agents, alongside the [UCP (Universal Commerce Protocol)](/glossary/ucp/).[^stripe-agentic] ## In a store The feed is the piece that touches every merchant. OpenAI asks for it in JSONL, one line per product or variant, with nine required fields: identifier, title, description, URL, brand, seller name, image, availability and price. It recommends titles of up to 150 characters and descriptions of up to 5,000, and warns that **a row without a recognizable availability value is rejected**.[^openai-feed-spec] Here is a product from a **fictional example store**, using the specification's fields: ```json { "item_id": "MOKA-INOX-6", "title": "Stainless steel stovetop espresso maker, 6 cups, induction-ready", "description": "18/10 stainless steel moka pot for 6 cups. Works on induction, gas and glass-ceramic stoves.", "url": "https://example-coffeemakers.com/products/moka-inox-6", "brand": "Example Brand", "seller_name": "Example Coffeemakers", "image_url": "https://example-coffeemakers.com/img/moka-inox-6.jpg", "price": "39.90 USD", "availability": "in_stock" } ``` According to the specification, a product like this is enabled for search and disabled for checkout inside ChatGPT unless the merchant says otherwise, and being enabled does not guarantee it will be shown.[^openai-feed-spec] Clione builds that feed from the enriched catalog and uploads it every day to the SFTP account OpenAI gives the merchant; whether the products appear, and where, is up to OpenAI. Reading the March 2026 shift as the end of the ACP. What OpenAI stopped prioritizing was checkout inside the chat; the protocol became **the way merchants send their catalog to ChatGPT**.[^openai-discovery] For a store, the ACP today is mostly a well-built feed. ## How to check 1. **If you sell on Shopify**, your products already reach ChatGPT through Shopify Catalog; check that each product's data in your admin is complete.[^openai-discovery] 2. **If not, read the feed specification** and request direct feed access from OpenAI's help center.[^openai-shopping-help] 3. **Validate each row before sending it**: the required fields, an allowed availability value and the price with its currency.[^openai-feed-spec] 4. **Ask your provider which version it implements.** The ACP changes through dated versions, and the stable one is the one from April 17, 2026.[^acp-repo] ## Related concept: UCP The [UCP (Universal Commerce Protocol)](/glossary/ucp/) solves the same problem from Google and Shopify: how an agent discovers, buys and tracks an order in a store. Both protocols keep the merchant as the seller and both can travel over MCP.[^acp-site][^google-ucp-launch] What differs, in practice, is where they are used: the ACP feeds ChatGPT; the UCP feeds [Google's AI Mode](/glossary/google-ai-mode/) and [Gemini](/glossary/gemini/). Stripe supports both for selling through agents,[^stripe-agentic] so for many stores it is not an either-or choice. To go further, [agentic commerce](/glossary/agentic-commerce/) separates discovering, recommending and buying, and the [agentic commerce reading path](/learn/agentic-commerce/) lays out the rest of the protocols.