ACP — Agentic Commerce Protocol

What the spec defines

Per the published specification at agenticcommerce.dev, ACP is openly licensed (Apache 2.0) and defines merchant-side endpoints for the checkout lifecycle — creating, updating, completing, and canceling checkout sessions — plus a PSP-side delegated-payment mechanism in which the payment provider issues a scoped token the merchant captures against, bounded by an allowance (amount, currency, merchant, expiry). The buyer's underlying credential never reaches the merchant. Stripe is the first named compatible payment provider, via its Shared Payment Token mechanism, per the spec materials as of mid-2026.

The practical effect: a buyer says "buy it" inside ChatGPT, the agent calls the merchant's ACP endpoints with the scoped payment token, and the order lands in the merchant's system — without the buyer touching the storefront.

Why it matters for ecommerce

ACP changes which signals matter at the moment of purchase. When the conversation is the storefront, feed completeness, schema accuracy, and endpoint reliability outweigh hero photography and persuasion copy. A catalog whose price, availability, variants, and policies are machine-readable is sellable through an agent; one whose facts live in prose is not, regardless of how it converts humans.

For Shopify brands the path is indirect: Shopify wraps agentic checkout through Shopify Agentic Storefronts rather than asking merchants to implement protocol endpoints themselves. Direct ACP implementation is realistic mainly for custom backends with engineering teams — and even then, the pilot-stage caveat applies to volume expectations.

How ACP relates to UCP and AP2

ACP is one of two major agent-checkout stacks. Google's UCP (Universal Commerce Protocol) covers the equivalent lifecycle for Google's surfaces (AI Mode, Gemini), with AP2 (Agent Payments Protocol) as a separate payments layer; ACP bundles its payment hand-off through the PSP's delegated token. Both are in pilot as of mid-2026, and the merchant-side groundwork they assume — complete product data, reliable availability, discoverable policies — is shared. That shared groundwork, not protocol selection, is the actionable work for most brands today.

Hedges worth keeping

Three, all dated mid-2026: the protocol is in pilot with a limited merchant set, so volume claims should stay conservative; the spec is evolving, so implementation details (discovery mechanisms, supported PSPs) should be checked against the current published version rather than summaries; and no third-party tool — including eCommerce Insights — implements ACP end to end for you. Scoring readiness is a different, honest claim.

How eCommerce Insights treats ACP

As a readiness target, not an integration. The agent-readability score checks the PDP groundwork agent checkout assumes — structured product data, machine-readable price and availability, admitted crawlers, discoverable policies, and checkout wiring where applicable. The ACP guide covers the spec in implementation-level detail.

Related terms

• UCP (Universal Commerce Protocol) — Google's counterpart lifecycle protocol.
• AP2 (Agent Payments Protocol) — the payments layer on the Google stack.
• ChatGPT Instant Checkout — the consumer feature ACP backs.
• Shopify Agentic Storefronts — how Shopify merchants get this without implementing it.
• Agentic commerce — the three-stage shift ACP's checkout stage belongs to.