How ACP Works for Merchants
> For a merchant, ACP implementation means two parallel workstreams: preparing a structured product feed with the required data fields, and implementing the ACP Checkout Session API endpoints on your commerce stack so that AI agents can create, update, and complete purchases on behalf of buyers.
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What Does ACP Require from a Merchant?
ACP is a two-layer requirement: the product data layer and the checkout API layer. These are complementary but distinct, and a merchant must address both to be fully ACP-compliant.
The product data layer is about catalog quality. An ACP-compatible product feed must express what each product is, what it costs, whether it is in stock, what variants exist, what the return policy is, and what buyers commonly ask about it — all in structured, machine-readable fields. This is the data an AI agent reads when deciding whether to recommend a product. The more complete and accurate this data is, the better the merchant performs in agent-driven product discovery.
The checkout API layer is about transactional infrastructure. A merchant implementing ACP exposes five REST endpoints under their domain that ChatGPT and other ACP-compatible agents can call to start, update, complete, and cancel purchase sessions. These endpoints sit on top of the merchant's existing e-commerce platform; they do not replace it. The merchant keeps their PSP, order management system, and fulfilment logic; the ACP endpoints are the bridge between the agent's checkout interface and the merchant's back end.
Merchants who want to be discoverable and recommendable without yet supporting Instant Checkout can prioritise the product data layer first. Merchants who want to support programmatic purchasing must implement both layers.
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How ACP Works: Step-by-Step for Merchants
Step 1: Prepare your ACP-compatible product feed. Build or generate a structured product feed that meets ACP data requirements. Required fields include product ID, title, price, currency, and availability. Recommended fields include GTIN/MPN, images, product description, structured variants (`variant_dict`), trust signals (`accepts_returns`, `return_deadline_days`, `is_digital`), AI Q&A pairs (`q_and_a` as a JSON array), structured reviews, and sale pricing (`sale_price`, `sale_price_start_date`, `sale_price_end_date`). The feed format for ChatGPT Shopping compatibility is JSON-LD.
Step 2: Host your feed at a stable, accessible URL. The feed must be hosted at a consistently accessible HTTPS URL. Feeds should be updated as frequently as possible to keep pricing and availability accurate for agents making real-time purchasing decisions.
Step 3: Implement the ACP Checkout Session endpoints. Expose five REST endpoints at your domain:
- `POST /checkout_sessions` — create a session with items and optional fulfillment address
- `POST /checkout_sessions/{id}` — update a session with address, fulfillment option, or item changes
- `POST /checkout_sessions/{id}/complete` — complete checkout by passing a PSP payment token
- `POST /checkout_sessions/{id}/cancel` — cancel an in-progress session
- `GET /checkout_sessions/{id}` — retrieve current session state
Step 4: Integrate with a supported PSP for Delegated Payments. ACP's Delegated Payment model allows an AI agent to collect a payment token from a buyer via a supported PSP — Stripe, Adyen, or Braintree — and relay it to the merchant's `complete` endpoint. The merchant processes this token through their existing PSP integration. Settlement, reconciliation, and chargebacks all happen on the merchant's own PSP account.
Step 5: Configure order webhook delivery. After an order is created, the merchant must emit `order.created` and `order.updated` webhook events to the endpoint provided by the AI platform. Each event includes the current order status — which can be `created`, `manual_review`, `confirmed`, `canceled`, `shipped`, or `fulfilled`. Webhooks are signed using HMAC; merchants must verify the signature on receipt to ensure authenticity.
Step 6: Pass integration certification. To support Instant Checkout in ChatGPT, merchants must pass conformance checks covering schema correctness, error code standards, rate limit handling, and webhook delivery reliability. The ACP specification is open to all implementers; the ChatGPT Instant Checkout channel currently operates through an approved partner program.
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Key Requirements at a Glance
| Layer | Requirement | Notes | |---|---|---| | Product data | JSON-LD feed with required product fields | Foundation for agent discovery and evaluation | | Trust signals | `accepts_returns`, `return_deadline_days`, `is_digital` | Required for agent purchase confidence | | Checkout API | Five REST endpoints on HTTPS | Required for programmatic purchasing | | PSP integration | Stripe, Adyen, or Braintree — token relay model | Required for Delegated Payments | | Webhooks | `order.created` and `order.updated` events | Required to keep agent and buyer in sync | | Certification | Schema, errors, rate limits, webhook reliability checks | Required for ChatGPT Instant Checkout |
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Why It Matters for Merchants
The ACP implementation effort is finite and bounded. Unlike open-ended SEO work, the ACP requirement set is a defined specification: implement these endpoints, include these fields, connect to one of these PSPs. A merchant who completes this implementation becomes reachable by every ACP-compatible AI agent — not just ChatGPT today, but any future agent that adopts the open standard.
Merchants retain full ownership of every element of the transaction. The merchant's PSP settles the payment. The merchant's OMS creates the order. The merchant's fulfilment system ships the goods. The merchant's customer support team handles post-purchase interactions. ACP does not extract margin or insert an intermediary — it is an interface layer that opens the merchant's store to a new purchase channel.
For merchants in categories where AI assistants are already actively used for shopping research — electronics, apparel, beauty, health — early ACP compliance creates a first-mover advantage in a channel that is still establishing its competitive landscape.
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FeedBridge Relevance
FeedBridge covers the product data layer of ACP implementation fully. The platform generates ACP-compliant JSON-LD feeds that include all documented ACP product data fields: trust signals (`accepts_returns`, `return_deadline_days`, `is_digital`), `variant_dict` structured variants, JSON-array Q&A pairs, structured reviews as JSON arrays, and sale pricing fields with start and end date support. These are generated by FeedBridge's Universal AI Engine across eight product verticals — food, electronics, apparel, beauty, home, health, digital, and other — and applied through the Preview & Apply Workflow so merchants can review enrichment before publishing.
The resulting feed is hosted at a CDN-backed unique URL per brand, with configurable scheduling, feed health monitoring, dead URL checks, and email alert preferences. FeedBridge does not implement the ACP Checkout Session API endpoints on behalf of merchants — those must be built on the merchant's own commerce stack or through an ACP-integrated PSP partner. FeedBridge's scope is the product data and feed delivery layer that feeds into that checkout.
The UCP Dashboard Hub in FeedBridge provides a compliance scorecard and capability checklist for UCP protocol implementation, which complements ACP coverage for merchants who want to be reachable across both ChatGPT Shopping and Google AI Mode simultaneously.
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Frequently Asked Questions
Q: Do I need a developer to implement ACP? A: The checkout API layer requires engineering work — implementing five REST endpoints, connecting to a PSP, and configuring webhooks. The product data layer can be managed through a platform like FeedBridge without engineering involvement. Merchants typically start with the data layer and bring in development resources for the API layer.
Q: Can I use my existing Shopify or WooCommerce store for ACP? A: Your existing store is the back end that ACP endpoints connect to. There is no native ACP plugin for Shopify or WooCommerce at this time; merchants typically implement the checkout session endpoints as a middleware layer that reads from and writes to their store's order management system. FeedBridge handles the product feed layer for Shopify and WooCommerce merchants natively through live store sync integrations.
Q: What PSP do I need for ACP Delegated Payments? A: ACP supports three PSPs for its Delegated Payment model: Stripe, Adyen, and Braintree. Merchants using a different PSP would need to migrate or add one of these three to support the credential relay flow.
Q: What happens to my customer data after an ACP checkout? A: The `complete` endpoint returns a `buyer` object containing the buyer's name, email, and phone (if provided). This data flows to the merchant as part of the order, allowing the merchant to follow up through their own CRM and re-engage the buyer for future purchases.
Q: Is ACP free to implement? A: The ACP specification is open and freely available. There are no licensing costs for implementing the protocol. Standard PSP transaction fees apply when processing payments through Stripe, Adyen, or Braintree, as they do for all commerce processed through those platforms.
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Related Topics
Parent hub: ACP Foundations
Related concepts:
- What Is ACP?
- ACP Instant Checkout in ChatGPT Explained
- ACP Merchant Onboarding Requirements
- ACP Product Feed Requirements
Breadcrumb:
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Source Documentation
| Claim | Source | Source Class | Reference | |---|---|---|---| | ACP five checkout session endpoints, request headers, lifecycle | OpenAI ACP Checkout Spec | T1 – Official ACP Docs | https://developers.openai.com/commerce/specs/checkout/ | | Supported PSPs: Stripe, Adyen, Braintree | OpenAI ACP Checkout Spec | T1 – Official ACP Docs | https://developers.openai.com/commerce/specs/checkout/ | | Order status values: created, manual_review, confirmed, canceled, shipped, fulfilled | OpenAI ACP Checkout Spec | T1 – Official ACP Docs | https://developers.openai.com/commerce/specs/checkout/ | | ACP trust signals, variant_dict, q_and_a, reviews, sale price fields | FeedBridge Platform Capabilities April 2026 v2.0 | T1 – FeedBridge Internal | FeedBridge-Platform-Capabilities-April2026.md | | FeedBridge JSON-LD ACP feed, CDN hosting, feed health monitoring, Shopify/WooCommerce sync | FeedBridge Platform Capabilities April 2026 v2.0 | T1 – FeedBridge Internal | FeedBridge-Platform-Capabilities-April2026.md |