Agentic Commerce Protocol

The Agentic Commerce Protocol is an open standard that lets a buyer’s AI agent complete a purchase through a business’s existing checkout, maintained by OpenAI and Stripe and published under the Apache 2.0 license.

Status. The first version was released on 29 September 2025. Versions are dates, the latest stable one is 2026-04-17, and the repository labels the specification beta. A Technical Steering Committee governs changes, and the founding maintainers keep a veto as a last resort.

How checkout works. The merchant implements the Agentic Checkout API and remains the system of record for orders, payments, taxes and compliance. The agent drives a checkout session:

1. POST /checkout_sessions creates a session from items and optional buyer details.
2. POST /checkout_sessions/{id} updates items, address or fulfillment option.
3. GET /checkout_sessions/{id} returns the current authoritative state.
4. POST /checkout_sessions/{id}/complete submits payment data and must create an order.
5. POST /checkout_sessions/{id}/cancel cancels a session that is still open.

Every request carries a bearer token and an API-Version header. Every POST carries an Idempotency-Key, and clients should sign requests with Signature and Timestamp headers. Amounts are integers in minor units. Order updates reach the agent platform through signed webhooks.

Delegated payment. A separate Delegate Payment API turns a card credential into a token for the merchant’s payment service provider. An allowance limits the token to one merchant, one checkout session, a maximum amount and an expiry time. The allowance example from the specification:

{"reason": "one_time", "max_amount": 100000, "currency": "usd", "checkout_session_id": "csn_01HV3P3XYZ789", "merchant_id": "merchant_12345", "expires_at": "2026-02-15T18:30:00Z"}

Discovery and transports. Release 2026-04-17 added a public discovery document at /.well-known/acp.json and an MCP binding that exposes the five checkout operations as MCP tools.

Neighbouring terms. AP2 records what a user authorized an agent to buy, and x402 carries a payment inside an HTTP exchange. The Universal Commerce Protocol covers similar checkout ground as a separate project. IBM’s Agent Communication Protocol also used the abbreviation ACP, but it is unrelated.