> ## Documentation Index
> Fetch the complete documentation index at: https://docs.getsly.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# ACP (Agentic Commerce Protocol)

> Stripe + OpenAI's protocol for agent-driven checkout. Card-network-native.

ACP is the Agentic Commerce Protocol developed by Stripe and OpenAI. It defines how AI agents conduct checkout against merchants in the Stripe / OpenAI ecosystem — notably including the OpenAI Agent marketplace and ChatGPT shopping.

Sly provides a full ACP implementation compatible with the published spec, plus server-side policy enforcement (KYA tiers, wallet limits) that ACP itself doesn't define.

## Core concept: the checkout session

ACP works in terms of **checkout sessions** — stateful objects that represent a purchase in progress. The session transitions through states as the agent and merchant interact.

```
created ─▶ pending_payment ─▶ paid ─▶ fulfilled
                   │
                   ▼
               failed / expired / cancelled
```

## Create a checkout session (agent side)

```bash theme={null}
curl -X POST https://api.getsly.ai/v1/acp/checkouts \
  -H "Authorization: Bearer agent_..." \
  -H "Content-Type: application/json" \
  -d '{
    "merchant_id": "mer_stripe_...",
    "items": [
      { "sku": "widget-pro", "quantity": 2, "unit_price": "24.99", "currency": "USD" }
    ],
    "shipping_address": { ... },
    "payment_method": "card"
  }'
```

Response:

```json theme={null}
{
  "id": "acp_chk_...",
  "status": "pending_payment",
  "total": "49.98",
  "currency": "USD",
  "client_secret": "cs_...",
  "expires_at": "2026-04-22T14:30:00Z"
}
```

## Complete payment

```bash theme={null}
curl -X POST https://api.getsly.ai/v1/acp/checkouts/acp_chk_.../complete \
  -H "Authorization: Bearer agent_..." \
  -d '{
    "payment_method_id": "pm_..."
  }'
```

Payment is executed synchronously against the card network (or async for deferred methods). On success the session transitions to `paid`; on failure, to `failed` with a reason code.

## Fulfillment

Merchants report fulfillment back to Sly; buyers poll or subscribe to `acp.checkout.fulfilled` webhooks:

```bash theme={null}
curl https://api.getsly.ai/v1/acp/checkouts/acp_chk_.../events \
  -H "Authorization: Bearer agent_..."
```

## Endpoints

| Endpoint                              | Purpose                              |
| ------------------------------------- | ------------------------------------ |
| `POST /v1/acp/checkouts`              | Create checkout session              |
| `GET /v1/acp/checkouts`               | List sessions                        |
| `GET /v1/acp/checkouts/:id`           | Get session state                    |
| `PATCH /v1/acp/checkouts/:id`         | Update (e.g. swap payment method)    |
| `POST /v1/acp/checkouts/:id/complete` | Complete payment                     |
| `POST /v1/acp/checkouts/:id/cancel`   | Cancel session                       |
| `POST /v1/acp/checkouts/batch`        | Batch checkout (marketplace baskets) |
| `POST /v1/acp/checkouts/:id/refund`   | Refund completed checkout            |

Plus 26+ sub-resource endpoints for items, shipping, discounts, tax calculation, and webhook replay. See [API reference](/api-reference) for the complete list.

## Differences from the canonical ACP spec

Sly's implementation adheres to the Stripe/OpenAI spec, plus:

* **KYA tier enforcement** — agents cannot complete checkouts that exceed their [KYA tier limits](/agents/kya-tiers)
* **Wallet policies** — per-merchant allowlists/blocklists enforce at checkout time
* **Composition** — checkouts can be funded by UCP tokens, AP2 mandates, or x402 bridged payments
* **Approval workflow** — checkouts above a policy threshold auto-trigger human approval

## When to use ACP

* Merchant is on Stripe Connect or listed in the OpenAI Agent marketplace
* Buyer is a ChatGPT agent or OpenAI-ecosystem agent
* You want card-network-native payment (Visa, Mastercard, Amex)
* You need the Stripe / OpenAI compliance posture out of the box

For non-Stripe merchants or non-card rails, prefer [UCP](/protocols/ucp).