How can I auto-fill form values in Webflow based on the URL querystring?

To auto-fill form values in Webflow based on the URL querystring, you can utilize custom code and the Webflow API. Here's a step-by-step guide on how to achieve this:

1. Add a form element to your Webflow project and give each input field a unique class or ID.

2. Go to the "Settings" tab of your project and enable the "Custom Code" section. In the "Head Code" section, you'll add the necessary JavaScript code to retrieve and set the querystring values.

3. In the "Code" section, click on the "Add Custom Code" button and select "Before tag" to add the following JavaScript code:

```javascript
// Get querystring parameters
const queryString = window.location.search;
const urlParams = new URLSearchParams(queryString);

// Fill form values
document.addEventListener("DOMContentLoaded", function() {
// Example: input field with ID "name"
const nameInput = document.getElementById("name");
if(urlParams.has("name")) {
nameInput.value = urlParams.get("name");
}
});
```

4. Replace `"name"` and `"nameInput"` with the appropriate ID or class of your input field. Repeat the code block for each input field you want to auto-fill.

5. Publish your site to see the changes live. Now, when you visit a URL with querystring parameters like `https://yourwebsite.com/contact?name=John`, the form's input field with ID "name" will be automatically filled with "John".

It's important to note that this solution requires some technical knowledge and the use of custom code. Additionally, using querystring values in forms may raise security concerns, so make sure to validate and sanitize user input to prevent any potential issues.