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

# Checkout Links

> Create direct checkout links to SellAuth with zero JavaScript or SDK integration.

## Integration Overview

**Checkout Links** allow you to create a URL that **instantly creates a SellAuth checkout session when opened**.

This is the **simplest possible integration**: no JavaScript, no SDK, no embeds, no custom logic.

You can use these links behind **buttons, anchors, images, emails, or ads**, and they will open the SellAuth checkout automatically.

When a customer opens a Checkout Link:

1. A checkout session is created server-side
2. A short loading screen is shown
3. A background CAPTCHA is solved automatically
4. The customer is redirected to the SellAuth checkout page

The loading spinner is **intentional** and required for bot protection.

## HTML Integration

All you need to do is create a link or button that points to the Checkout Link URL:

```html theme={null}
<a
  href="https://<your shop>.mysellauth.com/checkout-link?cart[0][productId]=<product id>&cart[0][variantId]=<variant id>&cart[0][quantity]=<quantity>"
  target="_blank"
>
  <span>Buy Now</span>
</a>
```

## Parameters

### `cart` (required)

An array of cart items.

| Field | Type | Required | Description |
| - | - | - | - |
| `cart[index].productId` | number | Yes | Product ID |
| `cart[index].variantId` | number | Yes | Variant ID |
| `cart[index].quantity` | number | Yes | Quantity (1-100000) |
| `cart[index].parentVariantId` | number \| null | No | ID of the variant this addon product belongs to |

### Other Parameters (optional)

| Parameter | Type | Required | Description |
| - | - | - | - |
| `currency` | string \| null | No | 3-letter currency code |
| `email` | string \| null | No | Customer email |
| `affiliate` | string \| null | No | Affiliate / referral code |
| `utm_source`, `utm_medium`, `utm_campaign`, `utm_term`, `utm_content` | string \| null | No | Campaign attribution stored on the invoice, max 100 characters each. The external referrer host is recorded automatically when the link is opened from another site. |

## Example with all parameters and multiple cart items

```txt theme={null}
https://<your shop>.mysellauth.com/checkout-link?cart[0][productId]=1&cart[0][variantId]=1&cart[0][quantity]=1&cart[1][productId]=3&cart[1][variantId]=3&cart[1][quantity]=2&cart[1][parentVariantId]=1&currency=USD&email=john.doe@email.com&affiliate=CREATOR123
```

<Note>Need more control (custom items, prefilled details, server-side creation)? See the [Checkout API](/developers/checkout-api).</Note>


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