“Agentic commerce” is the phrase of the year in ecommerce, and underneath the buzzword is a concrete piece of plumbing: the Agentic Commerce Protocol, or ACP. If AI assistants are going to help people shop — and increasingly buy — there has to be a standard way for an assistant to talk to a merchant’s store, place an order and take payment. ACP is that standard. This guide explains what it is, how a purchase actually flows through it, and what a UK merchant needs to take part.
What ACP actually is
The Agentic Commerce Protocol is an open standard, co-developed by OpenAI and Stripe, that lets an AI agent complete a purchase on a shopper’s behalf. It defines how the agent shares a shopper’s intent and cart with the merchant, how the merchant confirms availability and price, and how payment is captured securely — without the merchant having to build a bespoke integration for every AI assistant that comes along.
Crucially it’s open. It was published for any merchant, platform or payment provider to adopt. PayPal joined as an ACP-compatible payment provider, and the intent is that ACP becomes shared infrastructure rather than one company’s walled garden — the same way card networks or messaging standards work.
ACP is the common language an AI shopping agent and your store use to agree on “here’s the item, here’s the price, here’s the payment” — so any assistant can transact with any store that supports it.
How an agentic purchase flows
Walk through what happens when a shopper asks an AI assistant to buy something:
- Discovery. The shopper describes what they want. The assistant surfaces candidate products — drawn from merchant product feeds, not by crawling websites.
- Selection. The shopper picks one. The assistant assembles a cart: item, variant, quantity, price.
- Handshake. Over ACP, the assistant sends that cart to the merchant, which confirms the product is real, in stock and correctly priced — straight from live data.
- Payment. Payment is captured through an ACP-compatible provider (Stripe, PayPal), tokenised so the merchant is paid and the shopper’s details stay protected.
- Fulfilment. The order lands in the merchant’s normal system and is fulfilled like any other.
Every step past discovery depends on the merchant having accurate, live product data. If the feed the assistant discovered you from is stale — wrong price, out of stock, wrong variant — the handshake fails and the sale is lost. Good data isn’t a nice-to-have in agentic commerce; it’s the thing the whole transaction is built on.
ACP and the discovery-first shift
It’s worth being clear-eyed about where this stands in 2026. OpenAI built ACP to power Instant Checkout inside ChatGPT — then pivoted towards discovery, letting shoppers research in ChatGPT and buy on the retailer’s own site. So did ACP become irrelevant? No. ACP is the rails; the pivot was about which stop the train currently ends at.
The protocol still exists, still has backers, and still defines how agentic checkout works when and where it happens — a marketplace here, a specific retailer there, a future re-expansion of in-chat buying. And other players are building the same rails: Google has published its own agent-payments work, and every major assistant is heading in this direction. Whether a given shopper checks out in-chat or on your site today, the merchant-side requirement is identical: a clean, complete, real-time product feed.
What a merchant needs to take part
You don’t need to implement the ACP spec yourself — your platform and payment provider handle the protocol. What you need to bring is your catalogue, in the right shape:
- A structured product feed in each AI channel’s format (ChatGPT uses JSONL delivered via SFTP). This is what makes you discoverable in the first place — see the ChatGPT product feed guide.
- Accurate, live price and availability, refreshed on a schedule, so the checkout handshake never fails on stale data.
- Complete identifiers and attributes — GTIN, brand, condition, variants — so agents can match your products confidently to specific requests.
- Descriptions written for machines to read, factual and specification-led, so the assistant chooses and describes your product accurately. An AI enrichment layer does this at scale.
Notice the pattern: everything a merchant needs for ACP is the same thing you need to be discovered by ChatGPT, Google’s AI shopping, Perplexity and the rest. Build one clean feed, maintained in real time, and you’re ready for all of it.
One feed, every agent
The strategic takeaway is simple. The agentic-commerce era doesn’t reward the merchant with the cleverest single integration — it rewards the merchant whose product data is complete, accurate and always up to date, delivered to every surface that matters. That’s a feed-management problem, and it’s exactly what Trajekt is built for: connect your store once, and generate spec-compliant feeds for ChatGPT, Google, Meta and more from a single source of truth — with AI enrichment and automatic delivery.
Want the foundation in place before agentic checkout comes back around? Read the ChatGPT product feed guide, see how OpenAI Ads build on the same feed, or start free with Trajekt today.
Trajekt is a UK-built product feed management platform covering Google Shopping, ChatGPT Shopping, OpenAI Ads, and AI commerce for UK merchants and agencies.
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