Agentic Commerce Protocol (ACP & UCP) — Definition

Canonical definition

The two protocols (and who maintains them)

ACP and UCP are different protocols from different companies — not two branches of one standard. A Magento store that wants full agentic visibility will typically need to support both, because they cover different AI surfaces.

• ACP — Agentic Commerce Protocol. Open standard created by OpenAI and Stripe (with Meta), released under the Apache 2.0 license in September 2025. It powers ChatGPT Instant Checkout and is the protocol behind ChatGPT Shopping product discovery. Specification at agenticcommerce.dev.
• UCP — Universal Commerce Protocol. A separate, Google-backed protocol announced in January 2026, aimed at Google Search AI Mode and Gemini. Distinct from ACP in origin, governance, and AI surface.

How agentic commerce works

1. A user asks an AI assistant for a product
2. The AI surfaces relevant products from a merchant’s structured feed
3. The agent builds a cart or recommendation set
4. The buyer confirms; the agent initiates checkout via the protocol
5. The merchant accepts the order, processes payment through its own provider, and handles fulfilment — remaining the merchant of record

ACP vs UCP comparison

UCP details are still emerging; treat its checkout and integration specifics as subject to change.

What an ACP integration requires

If you are not on a platform with built-in support (e.g. Shopify or Etsy), ACP is a development project. It generally requires three things:

• Product feed endpoint — structured product data served per the ACP spec, with regular updates
• Checkout API — REST endpoints to create, update, retrieve, complete, and cancel an agentic checkout session
• Payment integration — for example Stripe’s Shared Payment Token (SPT), which lets an agent initiate payment without exposing the buyer’s credentials

Costs to be aware of

At launch, OpenAI announced an approximately 4% merchant fee on completed ChatGPT Instant Checkout purchases, on top of standard payment-processor fees (for example Stripe’s ~2.9% + €0.30 equivalent at the time). These terms can change — always check the current Instant Checkout program terms. Product discovery in ChatGPT Shopping itself is free; shoppers pay nothing extra.

ACP for Magento

Both Magento Open Source and Adobe Commerce can participate in agentic commerce, but neither ships native ACP support — every layer is added through modules or custom development. A Magento ACP setup typically combines:

• Product feed — a structured catalog feed (titles, descriptions, price, availability, variants) served to the AI platform’s endpoint
• Checkout API — REST endpoints implementing the agentic checkout session lifecycle (create, update, get, complete, cancel)
• Shared Payment Token (SPT) — a Stripe payment primitive so an agent can pay without exposing buyer credentials
• Acceptance controls — per-agent or per-transaction allow/deny logic, plus monitoring
• Data consistency — feed, product page, and checkout responses must agree, or agents drop products that look unavailable

Because eligibility depends on structured, consistent product data rather than frontend UX, inconsistent data (e.g. wrong availability) is a revenue issue, not just a ranking one — an agent that hits a “sold out” wall simply moves on.

Strategic takeaway

Agentic commerce shifts ecommerce from “users browsing stores” to “AI agents executing purchases on behalf of users.” Visibility comes from structured, agent-readable data — and from supporting the right protocol for each AI surface.

These concepts form one chain: Magento AEO improves discoverability, AI Commerce Visibility improves eligibility to be selected, and ACP and UCP are the execution-layer standards that enable transaction completion once a product is chosen.

Primary sources

• OpenAI — Buy it in ChatGPT: Instant Checkout and the Agentic Commerce Protocol
• Stripe — Developing an open standard for agentic commerce
• Agentic Commerce Protocol — official site
• ACP specification on GitHub
• Stripe — Agentic Commerce Protocol documentation

Implementation tools (open-source)

• ChatGPT Shopping product feed
• ACP REST feed API
• Universal Commerce Protocol profile module