What is ACP? The Agentic Commerce Protocol, explained

What is ACP?

ACP (Agentic Commerce Protocol) is an open-source standard co-developed by OpenAI and Stripe, released in September 2025. It defines how an AI agent completes a purchase with a merchant on someone's behalf, from the moment the person says "buy it" to the moment the order is placed.

The simplest way to think about it: UCP and ACP are trying to solve the same problem, from two different camps. UCP comes from Google and Shopify. ACP comes from OpenAI and Stripe. Both want any agent to be able to buy from any store.

ACP was born inside ChatGPT. It launched alongside Instant Checkout, which let people buy from Etsy sellers without leaving the chat. You'd ask for a gift idea, ChatGPT would suggest something, and you could check out right there. Behind the scenes, ChatGPT used ACP to send the order to the merchant, and Stripe handled the payment.

The point of making it open was that merchants shouldn't have to build one integration for ChatGPT, another for the next AI assistant, and another for the one after that. Build ACP once, and any agent that speaks it can sell your products.

What ACP actually covers

ACP keeps things deliberately small. It covers three pieces:

1. Product feed: the merchant shares its catalog (products, prices, stock) in a standard format so the agent knows what's for sale.

2. Checkout: the agent creates an order, updates it if something changes (a different size, a new shipping address), and then completes it. The merchant stays in charge the whole time. It accepts or rejects the order, handles fulfillment, and owns the customer relationship.

3. Delegated payment: this is the clever part. The agent never sees your card number. Instead, the payment provider issues a one-time token that only works for this merchant, for this amount, for a limited time. The agent passes the token along, the merchant charges it, and your actual card details never touch the agent.

That token is the heart of ACP. It's like giving a valet a key that only starts the car and only works tonight, instead of handing over your whole keyring.

How ACP compares to UCP and AP2

The easiest way to see the difference is to look at what each one bundles together.

UCP splits the job in two. It handles the shopping (catalog, cart, checkout) and hands off to AP2 for the payment and the proof of permission. ACP does both in one package: the shopping flow and the payment token live in the same protocol.

The way they build trust is also different. AP2 relies on signed mandates, a written record of what the person agreed to. ACP relies on limiting the damage. The payment token is so narrow (one merchant, one amount, one window of time) that even if something goes wrong, there's only so much that can be charged.

Neither approach is wrong, and merchants don't really have to pick a side. Most brands selling at scale will end up supporting both, the same way most online stores today accept both Visa and Mastercard.

How a merchant adopts ACP

For most merchants, the answer runs through their payment provider or e-commerce platform.

If you already use Stripe, ACP support is close to plug-and-play through Stripe's Agentic Commerce Suite. Platforms like Wix, WooCommerce, BigCommerce, Squarespace, and commercetools offer integrations through it too. PayPal and Checkout.com have also signed on as payment providers, so you don't have to be a Stripe merchant to accept ACP payments.

If you're running your own backend, you'd implement the ACP checkout steps and plug in a payment provider that can issue and accept the one-time tokens. The spec is intentionally short, so the work is real but contained.

One thing worth knowing: in March 2026, OpenAI pulled back on Instant Checkout inside ChatGPT and shifted toward letting merchants run their own experiences inside the chat. The protocol itself kept going and is still actively updated. ChatGPT was the first place ACP showed up, not the only place it lives.

Where Beltic fits in

ACP limits how much can go wrong. It doesn't tell you whether something is going wrong.

Go back to the valet key. It only starts the car and only works tonight, which is great. But if the wrong person is holding it tonight, they can still drive off. ACP's payment token works the same way. It stops an agent from charging the wrong store or the wrong amount. It doesn't stop a hijacked agent, or one acting for a stolen account, from making a perfectly in-bounds purchase that the real customer later disputes.

ACP also gives the merchant the final say on every order: accept it or reject it. What it doesn't give the merchant is much to base that decision on.

That's the gap Beltic fills. Here's how it works in practice. An order arrives through ACP. Before the merchant accepts it, Beltic looks at who is behind the agent, what the person actually asked for, and whether this order matches that request and looks like normal behavior for them. It turns all of that into a clear risk read, and the merchant's own rules decide: accept the order, reject it, or ask the customer to confirm before it ships.

For the merchant, the payoff is the one that matters most in agentic commerce: fewer chargebacks and disputes on orders that looked fine on paper.

ACP makes sure an agent can only spend within a small, safe box. Beltic makes sure the right agent is holding the key.

This post is part of our series on agentic protocols. For how they all fit together, read What are agentic protocols? A plain-English guide.