ReCaptcha option allows adding a popular service providing anti-abuse security to protect your application. For integrating Google reCaptcha in an application, the app or web domain has to be registered to get the API keys.
You will see the required fields to fill for registering your domain:
Here is the example of how to fill it: Please choose reCAPTCHA v2 for the reCAPTCHA type field.
After filling this form with your valid data, you will be informed that your domain has been registered. There are two keys named as Site key and the Secret key will be given after registering the application.
These two keys are pasted into proper fields in the reCaptcha tab of Cost Calculator Settings.
Let's see how reCaptcha feature is working on our Calculator Send Form:
You can review here how to set up ReCaptcha v2 with the Contact Form 7 Plugin.