Cross-Domain Tracking

Track users seamlessly across multiple domains without losing session or attribution data.

When You Need Cross-Domain

Cross-domain tracking is needed when:

Checkout is on a different domain
You use subdomains with separate tracking
You have multiple properties that share users

yoursite.com → checkout.yoursite.com
     ↓
Without cross-domain: New session, lost attribution
With cross-domain: Same session, preserved attribution

How It Works

Convultra uses a _cvl URL parameter to transfer session data:

1. User on site-a.com
         ↓
2. Clicks link to site-b.com
         ↓
3. Convultra appends ?_cvl=<encoded-data>
         ↓
4. site-b.com SDK reads _cvl parameter
         ↓
5. Session and attribution continue seamlessly

The _cvl parameter contains:

Session ID
Click IDs (gclid, fbclid, etc.)
User ID (if identified)
UTM parameters

Setup

Configure Domains

In your SDK initialization, specify all domains:

Convultra.init({
  apiKey: 'your-key',
  endpoint: 'https://your-endpoint.com',
  crossDomainDomains: [
    'yoursite.com',
    'checkout.yoursite.com',
    'shop.yourbrand.com'
  ]
})

Automatic Link Decoration

The SDK automatically adds _cvl to links pointing to configured domains:

<!-- Before click -->
<a href="https://checkout.yoursite.com/cart">Checkout</a>
 
<!-- After SDK processes -->
<a href="https://checkout.yoursite.com/cart?_cvl=eyJzZXNzaW9uSWQiOi...">Checkout</a>

Install SDK on All Domains

Ensure the SDK is installed on every domain in the list.

Data Attributes Configuration

<script
  src="https://cdn.convultra.com/ultra.min.js"
  data-convultra-api-key="your-key"
  data-convultra-endpoint="https://your-endpoint.com"
  data-convultra-cross-domain-domains="yoursite.com,checkout.yoursite.com"
></script>

Manual Link Decoration

For dynamically created links:

// Get decorated URL
const url = Convultra.getCrossdomainLink('https://checkout.yoursite.com/cart')
 
// Result: https://checkout.yoursite.com/cart?_cvl=eyJz...

For JavaScript navigation:

document.getElementById('checkout-btn').addEventListener('click', () => {
  const targetUrl = 'https://checkout.yoursite.com/cart'
  window.location.href = Convultra.getCrossdomainLink(targetUrl)
})

Form Submissions

For forms that submit to another domain:

<form id="checkout-form" action="https://checkout.yoursite.com/process">
  <!-- Form fields -->
</form>
 
<script>
document.getElementById('checkout-form').addEventListener('submit', (e) => {
  const form = e.target
  
  // Add hidden field with cross-domain data
  const cvlInput = document.createElement('input')
  cvlInput.type = 'hidden'
  cvlInput.name = '_cvl'
  cvlInput.value = Convultra.getCrossdomainData() // Gets the encoded data
  form.appendChild(cvlInput)
})
</script>

What's Transferred

Data	Transferred	Purpose
Session ID	✅	Maintain session continuity
gclid	✅	Google Ads attribution
fbclid	✅	Meta Ads attribution
msclkid	✅	Microsoft Ads attribution
ttclid	✅	TikTok attribution
twclid	✅	Twitter attribution
UTM params	✅	Campaign tracking
User ID	✅	Identified user tracking
Referrer	✅	Traffic source

Security

Data Encoding

Cross-domain data is:

Base64 encoded
Time-limited (expires in 5 minutes)
Non-sensitive (no PII)

Validation

The receiving SDK validates:

Timestamp is within window
Domain is in allowed list
Data structure is valid

Common Scenarios

Main Site to Checkout

// Main site: yoursite.com
Convultra.init({
  crossDomainDomains: ['yoursite.com', 'checkout.yoursite.com']
})
 
// Checkout domain automatically receives session

Multiple Brand Sites

// Shared config across all brand sites
Convultra.init({
  crossDomainDomains: [
    'brand-a.com',
    'brand-b.com',
    'shop.example.com'
  ]
})

Subdomains

// Include all subdomains
Convultra.init({
  crossDomainDomains: [
    'example.com',
    'www.example.com',
    'shop.example.com',
    'checkout.example.com'
  ]
})

Troubleshooting

Session Not Continuing

Check domain list - Is target domain in crossDomainDomains?
Check SDK on both domains - Is it installed and initialized?
Check _cvl parameter - Is it in the URL?
Check expiry - Did user wait too long (>5 min)?

Debug Mode

Convultra.debug(true)
// Look for cross-domain logs in console

Verify Data Transfer

On the target domain:

// Check if cross-domain data was received
console.log(Convultra.getSessionId())
console.log(Convultra.getClickIds())

Limitations

Limitation	Details
Link decoration only	Doesn't work for direct URL entry
5-minute expiry	User must click within 5 minutes
JavaScript required	Needs SDK on both domains
Public data only	Doesn't transfer sensitive user data

Alternative: Server-Side

For more control, use server-side session linking:

// On first domain - get session
const sessionId = Convultra.getSessionId()
const clickIds = Convultra.getClickIds()
 
// Pass to your server
await fetch('/api/create-checkout', {
  body: JSON.stringify({ sessionId, clickIds })
})
 
// On second domain - restore session
Convultra.init({ ... })
Convultra.restoreSession({
  sessionId: sessionFromServer,
  clickIds: clickIdsFromServer
})

Next Steps

Attribution Models Bot Detection