--- title: "How to let ChatGPT and other AI agents buy from your store" description: "How to let ChatGPT and other AI agents buy from a custom store: product feed, ACP checkout endpoints, delegated payment, and what Medusa supports today." url: https://medusajs.com/kb/agentic-commerce/sell-through-ai-agents last_updated: 2026-10-29T06:55:50Z topic: "agentic-commerce" type: "how-to" applies_to: "Medusa v2.x" related: - "https://medusajs.com/kb/agentic-commerce/agentic-commerce-protocols.md" - "https://medusajs.com/kb/agentic-commerce/product-feeds-for-ai-agents.md" - "https://medusajs.com/kb/agentic-commerce/backend-for-ai-shopping-agents.md" - "https://medusajs.com/kb/agentic-commerce/ecommerce-mcp-servers.md" sources: - "https://docs.medusajs.com/resources/how-to-tutorials/tutorials/agentic-commerce" - "https://developers.openai.com/commerce/guides/key-concepts" - "https://developers.openai.com/commerce/guides/get-started" - "https://developers.openai.com/commerce/specs/file-upload/overview" - "https://developers.openai.com/commerce/specs/checkout" - "https://developers.openai.com/commerce/guides/production" - "https://agenticcommerce.dev/" - "https://developers.google.com/merchant/ucp" - "https://ucp.dev/" - "https://docs.stripe.com/agentic-commerce" - "https://shopify.dev/docs/agents" - "https://docs.medusajs.com/cloud/medusa-mcp" --- # How to let ChatGPT and other AI agents buy from your store > To let ChatGPT buy from a custom store, implement OpenAI's Agentic Commerce Protocol (ACP): a product feed, checkout session endpoints, delegated payment, and order webhooks. Google AI Mode and Gemini use UCP with AP2 instead. Medusa has an official ACP guide with example code; UCP and AP2 are custom work today. ## What does an AI agent need from your store to buy from it? An AI agent needs three layers from a store before it can complete a purchase: discovery, checkout, and payment. Each AI platform defines these layers in its own protocol. Selling through an assistant means implementing the protocol that assistant uses. | Layer | What it does | ChatGPT (ACP) | Google AI Mode and Gemini (UCP) | | --- | --- | --- | --- | | Discovery | The agent finds products, prices, and stock | Product feed sent to OpenAI | Catalog capability and Merchant Center shopping feeds | | Checkout | The agent builds a cart and places the order | Agentic Checkout Spec endpoints on your backend | UCP checkout capability over REST or MCP | | Payment | The agent hands over a scoped payment credential | Delegated Payment Spec, such as a Stripe Shared Payment Token | AP2 payment mandates | Assistants that support the [Model Context Protocol (MCP)](https://modelcontextprotocol.io/docs/getting-started/intro), such as Claude and ChatGPT, can also call tools that a store exposes through an MCP server. MCP is a general tool protocol, not a checkout standard. ## Before you start - A Medusa v2 application with published products, a region, and a sales channel. - The [Stripe Payment Module Provider](https://docs.medusajs.com/resources/commerce-modules/payment/payment-provider/stripe). Medusa's ACP guide notes that ChatGPT currently supports only Stripe as a payment provider. - Approval from OpenAI. Product feed onboarding in ChatGPT is open to approved partners, who apply at [chatgpt.com/merchants](https://chatgpt.com/merchants). - Public privacy policy and terms of service URLs. OpenAI's feed spec requires them for checkout eligibility. ## 1. Publish a product feed The product feed is how ChatGPT indexes your catalog. OpenAI's [file upload spec](https://developers.openai.com/commerce/specs/file-upload/overview) takes full catalog snapshots over SFTP, in parquet, jsonl.gz, csv.gz, or tsv.gz, at least once a day. In Medusa, you build the feed in a [workflow](https://docs.medusajs.com/learn/fundamentals/workflows) that reads products, prices, and inventory, and run it from a [scheduled job](https://docs.medusajs.com/learn/fundamentals/scheduled-jobs). Medusa's [ACP guide](https://docs.medusajs.com/resources/how-to-tutorials/tutorials/agentic-commerce) shows this pattern, but its upload step only logs the feed. You write the delivery code once OpenAI gives you access. ## 2. Add the checkout session endpoints OpenAI's [Agentic Checkout Spec](https://developers.openai.com/commerce/specs/checkout) defines the REST endpoints ChatGPT calls on your backend. In Medusa, each one is a custom API route that runs a workflow over Medusa's cart: - `POST /checkout_sessions` creates a cart with the requested items. - `POST /checkout_sessions/{id}` updates items, the address, or the shipping option. - `GET /checkout_sessions/{id}` returns the current state. - `POST /checkout_sessions/{id}/complete` completes the cart and creates the order. - `POST /checkout_sessions/{id}/cancel` cancels the session. ## 3. Authenticate and verify every request ChatGPT sends a bearer token and a `Signature` header with each checkout request. The Medusa guide adds a middleware that checks the token against a Medusa secret API key and verifies the signature with HMAC-SHA256, using the signing key OpenAI issues. ## 4. Charge the delegated payment OpenAI's [Delegated Payment Spec](https://developers.openai.com/commerce/specs/payment) passes your payment provider a one-time token with a maximum amount and an expiry. [Stripe's Shared Payment Token](https://docs.stripe.com/agentic-commerce) is the first compatible implementation. The Medusa guide passes this token to the Stripe provider when it completes the cart. ## 5. Send order webhooks ChatGPT tracks order status through webhooks you send. The Medusa guide uses a [subscriber](https://docs.medusajs.com/learn/fundamentals/events-and-subscribers) on `order.placed` and `order.updated` to post these events. ## 6. Pass certification and go live OpenAI's [production guide](https://developers.openai.com/commerce/guides/production) lists sandbox tests to complete before launch: sessions with and without an address, shipping updates, payment tokens, order completion, signed webhooks, errors, and idempotency. You stay the merchant of record and handle refunds and chargebacks. ## Which agentic commerce protocols does Medusa support? Medusa's support for agentic commerce protocols today: | Protocol | Used by | Status | What exists | | --- | --- | --- | --- | | ACP | ChatGPT Instant Checkout | Official guide | Tutorial with example code; feed delivery is a stub | | UCP | Google AI Mode and Gemini | Custom | No guide; build on API routes and workflows | | AP2 | UCP and A2A payments | Custom | No guide | | MCP | Claude, ChatGPT, and other MCP clients | Custom | Medusa MCP on Cloud is read-only and for store operators, not shoppers | ## How does this compare with Shopify? Shopify runs UCP-compliant MCP servers for every Shopify store, described in its [agent tools](https://shopify.dev/docs/agents) docs, for agent builders who shop on buyers' behalf: catalog search, Cart MCP, Checkout MCP, and order webhooks. On Shopify, the platform runs those endpoints. On a custom or headless backend such as Medusa, you implement each protocol yourself, on top of Medusa's cart, order, and payment logic. ## When is Medusa not the right choice? - You have no developer. ACP on Medusa is code your team writes and maintains. - You need Google AI Mode checkout without engineering work. Medusa has no UCP guide yet. - You sell products OpenAI prohibits, such as alcohol, nicotine, or weapons. No backend changes that. ## Common questions ### Does Medusa have a plugin for ChatGPT Instant Checkout? No. Medusa provides an official tutorial with example code for the Agentic Commerce Protocol, which you add to your own Medusa application. The tutorial's product feed upload step is a stub you complete after OpenAI approves you. ### Which payment providers work with ChatGPT checkout? OpenAI names Stripe's Shared Payment Token as the first implementation of its Delegated Payment Spec, with more providers to follow. Medusa's ACP guide uses the Stripe Payment Module Provider. ### Who is the merchant of record when ChatGPT places an order? The merchant is. OpenAI states it is not the merchant of record in the Agentic Commerce Protocol, so your store charges the payment and handles refunds and chargebacks. ### Can I sell through Google Gemini with Medusa? Not out of the box. Google AI Mode and Gemini use the Universal Commerce Protocol (UCP), and Medusa has no UCP guide yet, so you would build the endpoints as custom API routes and workflows. ## Documentation - [Implement Agentic Commerce (ChatGPT Instant Checkout) Specifications](https://docs.medusajs.com/resources/how-to-tutorials/tutorials/agentic-commerce) - [Stripe Payment Module Provider](https://docs.medusajs.com/resources/commerce-modules/payment/payment-provider/stripe) - [Scheduled Jobs](https://docs.medusajs.com/learn/fundamentals/scheduled-jobs) - [Medusa MCP](https://docs.medusajs.com/cloud/medusa-mcp) ## Related - [ACP vs UCP vs AP2 vs MCP: agentic commerce protocols explained](https://medusajs.com/kb/agentic-commerce/agentic-commerce-protocols.md) - [How to make your product catalog visible to AI assistants](https://medusajs.com/kb/agentic-commerce/product-feeds-for-ai-agents.md) - [Best ecommerce backend for building AI shopping agents](https://medusajs.com/kb/agentic-commerce/backend-for-ai-shopping-agents.md) - [Ecommerce platforms with MCP servers](https://medusajs.com/kb/agentic-commerce/ecommerce-mcp-servers.md)