How can I incorporate promo codes into my Webflow Free Trial landing page and display an error message for invalid codes? Can this be done without custom code and how can I maintain a database of valid promo codes for successful form submissions?

To incorporate promo codes into your Webflow Free Trial landing page without custom code, you can follow these steps:

1. Create a form on your landing page using Webflow's built-in form feature. Add an input field for the promo code where users can enter their code.

2. Create a collection in Webflow to store your valid promo codes. Each collection item will represent a separate promo code, and you can add additional fields like expiration date or discount amount if necessary.

3. Populate the collection with the promo codes you want to offer. You can do this manually by adding each promo code as a separate item, or you can import them using a CSV file.

4. Customize the success message for the form submission by editing the form settings. You can add a dynamic text field that displays a custom success message based on whether the promo code is valid or not.

5. Set up a validation rule for the promo code field in the form settings. You can choose the "Custom" option and write a rule that checks if the entered promo code matches any promo codes in your collection. If it doesn't match, you can display an error message.

6. To display the error message, you can use Webflow's interaction feature. Create a new interaction that triggers when the form submission fails due to an invalid promo code. Configure the interaction to show an error message element that was initially hidden, and make it visible with a fade-in animation.

7. If the promo code is valid, you can use Webflow's form submission actions to redirect the user to a specific page (e.g., a "success" page) and pass the promo code as a query parameter in the URL. You can then use that query parameter to retrieve and display the promo code on the success page if desired.

By following these steps, you can incorporate promo codes into your Webflow Free Trial landing page and display an error message for invalid codes, all without the need for custom code. Additionally, you can maintain a database of valid promo codes using Webflow's collection feature, making it easy to manage and update the available codes.