Server Side Testing

🚀 THIS ARTICLE WILL HELP YOU:

• Know why to use Server Side Testing
• Show Supported Platforms
• Understand Pre-requisites
• Understand Patterns
• Get a Checklist
• Know how to Troubleshoot

🚀 Why Use Server-Side Testing?

• Minimize content flash for server-rendered pages

• Support CDN edge delivery (e.g., Cloudflare Workers, Fastly, Akamai)

• Fully control variation logic backend-side

• Preserve experiment tracking integrity

🧭 Supported Patterns

🔧 Prerequisites

🍪 Pattern A – Cookie Hand-Off (with Tracking Script)

• Decide the variationId server-side

• Set a short-lived cookie:

  Set-Cookie: _conv_sptest=<experiment_id>:<variation_id>; Max-Age=10; Path=/; SameSite=Lax 

• Serve the HTML or redirect accordingly

• The Convert Tracking Script reads this cookie on load and tracks appropriately

CDN Examples:

Cloudflare Workers:

export default {
  async fetch(request) {
    const html  = await renderVariant(varId);
    const cookie = `_conv_sptest=${expId}:${varId}; Max-Age=10; Path=/; SameSite=Lax`;
    return new Response(html, {
      headers: {
        'Set-Cookie': cookie,
        'Cache-Control': 'private'
      }
    });
  }
}

AWS Lambda@Edge:

exports.handler = async (event) => {
  const req = event.Records[0].cf.request;
  req.headers['set-cookie'] = [{
    key: 'Set-Cookie',
    value: `_conv_sptest=${expId}:${varId}; Max-Age=10; Path=/; SameSite=Lax`
  }];
  return req;
};

Fastly Compute@Edge and Akamai EdgeWorkers examples are similar and also supported.

⚙️ Pattern B – Convert JavaScript SDK (Node.js only)

1. Install the SDK:
   npm install @convertcom/js-sdk


2. Server-side split logic and redirect

   import ConvertSDK from '@convertcom/js-sdk';
   
   const sdk = new ConvertSDK({ sdkKey: 'YOUR_PUBLIC_SDK_KEY' });
   await sdk.onReady();
   
   const ctx = sdk.createContext(visitorId);
   const variation = ctx.runExperience('exp-key');
   
   return Response.redirect(
     variation.id === '10002' ? 'https://site.com/new' : 'https://site.com/control',
     302
   );

3. SDK auto-tracks the visit—no cookie or tracking script needed

✅ Checklist

• Create the experiment and obtain experimentId / variationId

•  Choose Cookie or SDK path
•  Implement server/edge logic
• (Cookie path) Set _conv_sptest cookie before HTML
• (SDK path) Use runExperience() for bucketing
• Ensure CDN caching respects variation logic (use Cache-Control: private or cache keys)
•  QA: Inspect network requests or SDK logs

❗Troubleshooting

TL;DR:
Use cookie hand-off for quickest implementation with tracking script.
Use Convert SDK for full backend control, ideal for Split-URL or headless setups.