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

# Referral Code Tracking

> Track referral sources and campaign parameters using query strings on your Linkrunner subdomain

## Overview

Add query parameters to your Linkrunner subdomain URL to track referrals, campaigns, or custom data. When users click your link and install the app, retrieve these parameters through `getAttributionData()`.

**Works for both Android & iOS**

## Quick Example

Create a link with query parameters:

```
get.yourdomain.com?referrer=user_123&campaign=summer2024
```

When the user installs your app, call `getAttributionData()` to get the full URL and parse the parameters.

## Setup

### 1. Configure Your Subdomain

1. Go to [Linkrunner Settings → Domains](https://dashboard.linkrunner.io/settings?s=domains)
2. Add your subdomain (e.g., `get.yourdomain.com`)
3. Complete domain verification

<Note>
  No need to create campaigns in the dashboard. Just add query parameters to your subdomain URL and they'll be
  automatically captured.
</Note>

### 2. Create Your Links

**Basic referral:**

```
get.yourdomain.com?referrer=user_1
```

**Multiple parameters:**

```
get.yourdomain.com?referrer=user_1&campaign=summer2024&source=instagram
```

**With deep linking:**

```
get.yourdomain.com/product/123?referrer=user_456
```

## Retrieving Data

Call `getAttributionData()` early in your app lifecycle, then parse the `deeplink` field to extract your query parameters.

<Tabs>
  <Tab title="Android">
    Use `android.net.Uri` to parse the URL and `getQueryParameter()` to extract values.

    [See Android Usage Guide →](/sdk/android/usage#getting-attribution-data)
  </Tab>

  <Tab title="iOS">
    Use `URLComponents` to parse the URL and access the `queryItems` array.

    [See iOS Usage Guide →](/sdk/ios/usage#getting-attribution-data)
  </Tab>

  <Tab title="React Native">
    Use JavaScript's `URL` and `URLSearchParams` to parse and extract parameters.

    [See React Native Usage Guide →](/sdk/react-native/usage#getting-attribution-data)
  </Tab>

  <Tab title="Flutter">
    Use `Uri.parse()` and access the `queryParameters` map.

    [See Flutter Usage Guide →](/sdk/flutter/usage#getting-attribution-data)
  </Tab>
</Tabs>

## Common Use Cases

**Referral programs:** `?referrer=user_12345`

**Influencer tracking:** `?influencer=john_doe&platform=youtube`

**Campaign attribution:** `?campaign=summer_sale&source=instagram`

**Promo codes:** `?promo=SAVE20&referrer=email_campaign`

## Testing

1. Create a test link with query parameters
2. Uninstall your app completely
3. Click the link and install from the store
4. Verify parameters in `getAttributionData()`

<Warning>Always uninstall before testing. Attribution data is cached from the first install.</Warning>

## Troubleshooting

**No parameters showing up?** Verify your subdomain is configured correctly in the [dashboard](https://dashboard.linkrunner.io/settings?s=domains) and that the app was installed via your link (not directly from the store).

**Need help?** Contact [support@linkrunner.io](mailto:support@linkrunner.io)