ACP is maintained jointly by OpenAI, Stripe, and Meta under an Apache 2.0 license. The MAINTAINERS.md file at github.com/agentic-commerce-protocol/agentic-commerce-protocol names all three as governance partners. The current stable spec version is 2026-01-30 and 2026-04-17 is published as the next version, adding OpenRPC, cart, feeds, and webhook coverage.

Glossary

ACP: Agentic Commerce Protocol

Q: Does Shopify back ACP?

Shopify does not officially back ACP. Shopify backs the Universal Commerce Protocol (UCP) with Google. A third-party Shopify App Store listing from agenticcommerce.cloud integrates ACP for Shopify merchants, but it is an independent integrator and not an OpenAI/Stripe partner as of 2026-06-03.

Q: What does an ACP-ready merchant expose?

At minimum, five checkout endpoints (POST and GET /checkout_sessions, POST /checkout_sessions/{id}, POST /checkout_sessions/{id}/complete, POST /checkout_sessions/{id}/cancel) and capability negotiation through the proposed /.well-known/acp.json discovery file. The discovery file is RFC-stage and not yet promoted into the stable spec.

An open, Apache 2.0 protocol from OpenAI, Stripe, and Meta that lets AI agents discover, price, and complete purchases against merchant endpoints. Powers ChatGPT Instant Checkout.

Spec 2026-01-30 stable · 2026-04-17 next · Last updated 2026-06-03

In detail

ACP defines five merchant endpoints for the checkout lifecycle (POST and GET /checkout_sessions, POST /checkout_sessions/{id}, POST /checkout_sessions/{id}/complete, POST /checkout_sessions/{id}/cancel), plus a separate PSP-side endpoint at POST /agentic_commerce/delegate_payment that issues a vault token (prefix vt_...) constrained by an allowance object (max_amount, currency, merchant_id, expires_at, reason "one_time"). Lifecycle states run not_ready_for_payment → ready_for_payment → in_progress → completed (or canceled).

Discovery is in flux. The proposed mechanism is a JSON document at /.well-known/acp.json, but as of 2026-06-03 that file is RFC-stage and has not been promoted into the stable spec. Required request headers include Authorization: Bearer, Content-Type: application/json, and API-Version: YYYY-MM-DD.

The specification is published at github.com/agentic-commerce-protocol/agentic-commerce-protocol and documented at agenticcommerce.dev. Stripe is publicly named as the first compatible PSP through Shared Payment Token; Adyen and Braintree appear in the payment_handlers RFC as example PSPs but not as launch partners. Cartsy is the only merchant named as a live demo on agenticcommerce.dev.

Why it matters

ACP turns a ChatGPT conversation into a transaction. A buyer says "buy it" inside ChatGPT, the agent calls the merchant's checkout endpoints with a vault token from Stripe (or another supported PSP), and the merchant fulfills the order. The buyer never lands on the storefront. That changes which signals matter: schema, feed completeness, and endpoint reliability outweigh hero photography.

For Shopify brands the path is not direct. Shopify backs UCP rather than ACP, so the practical route to ChatGPT Instant Checkout on Shopify runs through Shopify Agentic Storefronts (wraps the OpenAI relationship without merchants touching ACP) or a custom backend that implements the five endpoints directly.

Example

A buyer in ChatGPT asks for a stainless water bottle under $40. The agent searches its product index, picks a SKU, and calls the merchant's POST /checkout_sessions with line items, buyer email, and shipping address. The merchant returns a session with pricing, taxes, and shipping options. ChatGPT confirms with the buyer. Stripe issues a vault token via POST /agentic_commerce/delegate_payment with an allowance for the order total. ChatGPT calls POST /checkout_sessions/{id}/complete with payment_data.instrument.credential.type "spt" and the vault token. The merchant fires its webhook to ChatGPT with the order_id and ships.

Related terms

UCP (Universal Commerce Protocol) — Google + Shopify counterpart that ships across Gemini and AI Mode.
Vault token (vs SPT) — the issued credential at /complete; SPT is the credential type name.
Shopify Agentic Storefronts — the channel that wraps ACP for Shopify merchants.
AP2 (Agent Payments Protocol) — Google's payments-layer sister to UCP.
Agentic commerce — the umbrella term ACP sits inside.

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Frequently asked questions

Who maintains ACP?

OpenAI, Stripe, and Meta, jointly, under Apache 2.0. The MAINTAINERS.md file at github.com/agentic-commerce-protocol/agentic-commerce-protocol names all three. Current stable spec is 2026-01-30; 2026-04-17 is published as next.

Does Shopify back ACP?

No. Shopify backs UCP with Google. A third-party Shopify app from agenticcommerce.cloud integrates ACP, but it is an independent integrator, not an OpenAI/Stripe partner as of 2026-06-03.

What does an ACP-ready merchant expose?

Five checkout endpoints, plus capability negotiation via the proposed /.well-known/acp.json discovery file, which is RFC-stage. The Delegate Payment endpoint is PSP-side, not merchant-side.

Related guides

Audit your store's ACP and UCP readiness with the free Agentic Readiness Grader.