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LanderLab allows you to automatically prefill fields in your quiz or form using URL parameters. This helps reduce friction, personalize the experience, and improve conversion rates by filling in data you already have. This feature is enabled by default - no extra setup is required beyond matching field names.

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How It Works

When a visitor lands on your page with parameters in the URL, LanderLab:
  1. Reads the parameters from the URL
  2. Matches them with input field Names
  3. Automatically fills the matching fields
Matching is not case-sensitive, so different variations will still work.

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Example

URL: 
https://yourlandingpage.com/?zip=12345
Setup:
  • Parameter → zip
  • Value → 12345
  • Input Name → zip, Zip, or ZIP
Result: The Zip Code field is automatically filled with 12345 when the page loads.

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How to Set It Up

  1. Identify the parameter you want to use (e.g. email, zip, aff_id)
  2. Open your quiz or form in LanderLab
  3. Select the input field you want to prefill
  4. Set the Name of the input to match the parameter
  5. Publish your page
  6. Test using a live URL with parameters

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Common Use Cases

  • Location targeting 
    ?zip=90210
  • Email personalization 
    [email protected]
  • Affiliate tracking 
    ?aff_id=123
  • Campaign tracking (UTMs) 
    ?utm_source=facebook&utm_campaign=summer

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Important Notes

  • Prefill works only on the live (published) page, not inside the builder preview
  • Input Name must match the parameter exactly (no extra spaces)
  • URL parameters must be properly formatted and encoded
  • Matching is case-insensitive
Tip: Combine prefill with Hidden Fields and tracking to automatically capture attribution data without asking users to fill it manually.