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

# Link URLs

> Dedicated URLs for launching Subtotal Link.

## Overview

Subtotal Link is a browser-based experience, offering maximum flexibility for brands and developers.

Each retailer has a dedicated **Link URL** that can be used to launch Subtotal Link when a customer is ready to link an account.

<Note>
  Prefer to let customers pick the retailer themselves? Use the [retailer-selection URL](/docs/subtotal-link/retailer-selection) — one URL that lists every retailer your program supports.
</Note>

<img src="https://mintcdn.com/typecastleinc/DaCtf-WNhcMVww3i/images/subtotal-link/link-url.png?fit=max&auto=format&n=DaCtf-WNhcMVww3i&q=85&s=28275dc3a5ff67e9589f68da5137b340" alt="subtotal link" className="rounded-lg border border-gray-100" width="1282" height="570" data-path="images/subtotal-link/link-url.png" />

## Query parameters

You can optionally include the following query parameters in a Link URL to provide additional context when a user links their account.

| Parameter       | Description                                                                                             | Example                                |
| :-------------- | :------------------------------------------------------------------------------------------------------ | :------------------------------------- |
| `customer_id`   | A unique identifier used to map connections to customer records across  external systems.               | `8a46e581-48ba-498a-9ad0-2ee72582e1af` |
| `redirect_url`  | The URL that customers should be redirected to after successfully linking their account.                | `https://example.com/profile`          |
| `connection_id` | The identifier of an existing connection (used to reauthenticate a connection or reconnect an account). | `01KFCQJPY9GN5BBB8ERHEWAZ7J`           |

Here’s an example of a complete Link URL that includes `customer_id` and `redirect_url`:

```
https://link.subtotal.com/tWGE4TJM
  ?customer_id=8a46e581-48ba-498a-9ad0-2ee72582e1af
  &redirect_url=https%3A%2F%2Fexample.com%2Fprofile
```

## Use cases

Link URLs allow your customers to connect their retailer accounts directly from any digital experience. You can use them wherever your brand engages customers — across web, mobile, or physical channels.

Common examples include:

* Loyalty programs and rewards experiences
* Landing pages for customer promos
* User profile pages within your app
* QR codes on packaging and in-store displays
* Social posts or digital ads

You can launch the linking experience from any digital surface — a website, mobile app, email, QR code, or social post — without requiring any native SDK or embedded component.