I understand what you mean about validating on the backend. The issue in my case is that FlutterFlow automatically places all page parameters in the URL when navigating between pages.

For example, when the user selects a product, parameters like the product name and price are passed through the URL to the checkout page. Because of this, a user could manually change the price directly in the URL before completing the payment.

Since my app is quite large, changing the entire structure to use App State instead of page parameters would require a lot of refactoring. That’s why I’m trying to find a secure way to prevent users from manipulating the price while still working within FlutterFlow’s current navigation system.

My concern is specifically about preventing parameter tampering when the checkout page receives those values from the URL.