Guide
Agentic Commerce Protocol (ACP)
Let AI agents complete purchases inside chat. ACP powers Instant Checkout in ChatGPT and beyond.
Last updated: February 3, 2026
Agentic Commerce Protocol (ACP)
Let AI agents complete purchases inside chat. The Agentic Commerce Protocol (ACP) powers Instant Checkout in ChatGPT and beyond. It’s an open standard that allows AI assistants to securely transact with businesses while merchants keep control of payments, order processing, and customer relationships.
Expose ACP endpoints so AI agents like ChatGPT can create, update, and complete orders while you stay merchant-of-record.
What is ACP?
ACP is to AI-driven checkout what HTTP is to the web — a universal language for transactions between AI agents, buyers, and merchants. Co-developed by OpenAI and Stripe, ACP is how ChatGPT lets users buy items without leaving the chat. When an AI agent initiates an order, the merchant’s own systems handle the actual payment and fulfillment.
ACP supports physical goods today and is designed to handle carts, subscriptions, and more over time.
How ACP Works
State Machine Overview
When ChatGPT starts a checkout, it creates a session via the merchant’s API. The session moves through states as it gets updated with shipping options, payment selections, and confirmation until it’s ready to complete. Merchants send updates via webhooks so the agent stays in sync.
Instant Checkout Example
User: “Buy the blue vase from Etsy.” The agent finds the product, creates a checkout session, asks the user to confirm, then completes payment using a scoped token. The merchant confirms the order and the agent reports success — all without leaving the chat UI.
Note
ACP requires explicit user confirmation and uses tokenized payments, so users stay in control and secure.
Instant Checkout vs Custom Agentic Integration
If you’re a Merchant
Apply to OpenAI’s Instant Checkout program, implement the ACP spec, and connect to a PSP that supports delegated or shared payment tokens.
If you’re an AI Platform
You can adopt ACP to enable purchases across your own assistant experiences, as long as you support the agent-side spec and merchant discovery.
If you’re a PSP
PSPs can offer tokenized payment flows so merchants can accept ACP transactions without exposing raw payment details.
Implementing ACP – Checklist
- Implement required REST endpoints (create, update, complete)
- Return full cart state on every response
- Support webhooks for order status
- Authenticate requests and verify signatures
- Handle idempotency and error states
- Test via ACP validator tool
Security and Trust Considerations
- Users confirm each purchase.
- Payment tokens are scoped to merchant + amount.
- Only minimal data is shared (shipping, contact details).
- Merchants can accept/decline transactions when needed.
Tools & Next Steps
- Validate your endpoints with the ACP Endpoint Validator
- Follow the ACP Getting Started Guide
- Compare UCP vs ACP
References & Evidence
Last Updated & Changelog
Last updated: 2026-02-03
Changelog
- 2026-02-03: Added implementation checklist, persona tabs, and trust guidance.
FAQ
Do I have to use Stripe to support ACP?
No. Stripe is the first PSP with ready support, but ACP is PSP-agnostic.
How is ACP different from UCP?
ACP focuses on agent-mediated checkout; UCP is broader across AI surfaces and discovery.
What is Instant Checkout in ChatGPT?
OpenAI’s program built on ACP for in-chat purchases with select merchants.
Can I integrate ACP if I’m not invited yet?
Yes. Implementing the spec now prepares you for future agents and approvals.
Is ACP open source?
Yes. It’s Apache 2.0 and community-driven.
Evidence & References
This content is based on official sources and ecosystem developments:
- ACP Get Started(Official Documentation)
- ACP Checkout Spec(Official Documentation)
- Agentic Commerce Protocol(Official Documentation)