We'll create fresh WordPress site with Spam Prevention for Contact Form 7 and Comments installed. You have 20 minutes to test the plugin after that site we'll be deleted.
Spam Prevention for WP Contact Form 7 and WordPress Comments.
This plugin adds a small code snippet to determine page scroll and add dynamically a unique token.
If the token doesn’t exists while submitting or call directly API then the incoming request will be rejected.
You can see how it works on SiteLint website.