reCAPTCHA is provided by Google. And we use reCAPTCHA v2 Checkbox . You can see more details from this link.
Create an API key pair
To start using reCAPTCHA, you need to sign up for an API key pair for your site. The key pair consists of a site key and secret key. The site key is used to invoke reCAPTCHA service on your site or mobile application. The secret key authorizes communication between your application backend and the reCAPTCHA server to verify the user's response.
Then you can get a site key and a secret key.
Configure in Casdoor
Create a new provider in Casdoor.
Select category as Captcha , type as reCAPTCHA . And you need to fulfill the site key and the secret key which is created by last step.
And you can click Preview botton to preview the style of this captcha.
Applied in application
Edit the application you want to configure in Casdoor. Select the provider just added and click the button Save.