Understanding the Agentic Commerce Protocol: Your Guide to Selling on ChatGPT

The e-commerce world just got a major upgrade with the launch of ChatGPT’s Instant Checkout, powered by the Agentic Commerce Protocol (ACP). If you haven’t checked it out yet, go to agenticcommerce.dev to see what it is. As a software engineer with zero experience in ACP let me tell you how I understand it (in simple terms).

Because I know that starting tomorrow, companies will start posting job listings asking for “5+ years of ACP experience”. So, let’s figure out what it takes to get shops selling on ChatGPT.

The Easy Way In: Etsy and Shopify Merchants

If you run your shop on Etsy or Shopify, you’ve hit the jackpot. These platforms are already integrated with ChatGPT’s Instant Checkout. No extra coding, no fuss. Your products are automatically eligible to appear when users search for stuff like “large t-shirt under $40.” OpenAI has done the heavy lifting, so Etsy and Shopify merchants are live (or rolling out soon) with zero setup. Lucky you!

For Everyone Else: Here’s the Work

If you aren’t on Etsy or Shopify, integrating with ChatGPT requires some effort. Don’t worry - it’s manageable, especially if you’ve built e-commerce APIs before. The process boils down to four steps:

• Registering
• Pushing products
• Setting up checkout endpoints
• Capturing payments

Let’s walk through it.

Step 0: Register as a Merchant

First, you need to get your shop approved by OpenAI. Head to chatgpt.com/merchants and fill out the merchant application form. It’s straightforward - provide details about the business, primary product categories, and whether you’re setting up a product feed or checkout integration. OpenAI reviews submissions on a rolling basis (expect 1-2 weeks). This step ensures only vetted merchants join the ecosystem, keeping things secure and trustworthy.

Step 1: Push Products to ChatGPT’s Collection

Once approved, you need to make ChatGPT aware of your products. This isn’t a public web search. ChatGPT uses a curated registry of approved ACP implementers to ensure compliance, accuracy, and trust. You’ll provide a product feed in a structured JSON format, either via an endpoint (e.g., /products/feed) or a file, following OpenAI’s Product Feed Spec.

Here’s what goes in the feed:

• Product details: ID, name, description, price, images.
• Variants: Size, color, etc. (e.g., “large blue t-shirt”).
• Availability: Stock status, shipping options.

You can update the feed every 15 minutes to reflect price changes or stock levels or whatever. Right now, product rankings are organic, based purely on relevance to the user’s query (e.g., “large t-shirt under $40”). No paid promotions yet, but I bet OpenAI will add that soon. Capitalism always finds a way!

Step 2: Set Up Checkout Endpoints with ACP

When a user finds a product in ChatGPT and clicks “Buy,” the magic happens through the Agentic Commerce Protocol. Think of ACP as a standardized API with predictable inputs and outputs that any AI agent (like ChatGPT) can understand. It’s like USB-C for commerce - universally agreed-upon formats that make life easier. My iPhone’s Lightning cable still drives me nuts in a USB-C world! But I digress.

Here’s how it works:

• Initiate Checkout: ChatGPT sends a POST request to your /checkout_sessions endpoint to start the process. The payload includes buyer info (name, email, maybe address—ChatGPT often pre-fills this to speed things up), items, and shipping details.
• Iterate and Update: As the user selects sizes, delivery options, or tweaks the cart, ChatGPT sends more requests to update the session (e.g., POST to /checkout_sessions/{id}).
• Complete Purchase: When the user enters payment details (e.g., card or Apple Pay), ChatGPT sends a secure payment token to /checkout_sessions/{id}/complete. You create the order and process the payment.

These endpoints map to your client’s existing backend (e.g., inventory, tax calculations), so you’re just wrapping your current APIs in ACP’s format.

Step 3: Capture Payments and Orders

Payments are handled via your existing provider, with Stripe being the easiest (it supports ACP’s Shared Payment Token out of the box). ChatGPT passes a secure token (no raw card data, keeping it PCI-compliant), and you charge it using your usual payment flow. If you’re not on Stripe, you’ll need to align your provider with ACP’s Delegated Payments Spec. Fulfillment (shipping, returns) stays with your existing systems, and you update ChatGPT via webhooks (e.g., “order shipped”).

Why This Matters

ACP makes AI-driven commerce predictable and scalable. Unlike custom APIs that vary by platform, ACP’s standardized endpoints mean your shop can work with ChatGPT today and other AI agents tomorrow. It’s a win for developers like me who love consistency. Plus, you stay in control as the merchant of record, owning the customer relationship without ChatGPT getting in the way.

Getting Started

Here’s the plan if you already want to get your e-shop on ChatGPT:

1. Apply: Submit the merchant form at chatgpt.com/merchants.
2. Build Feed: Create a product feed endpoint or file with your client’s product data.
3. Add Endpoints: Implement ACP’s /checkout_sessions and related endpoints, mapping to your existing APIs.
4. Test and Launch: Use OpenAI’s sandbox to test, get certified, and go live.

This is just a generic overview guide. Didn't want to get into the weeds too much. But if you have any questions or want some assistance making this work for your shop - get in touch, I'll be happy to help. 🙌