For some addons you can use Google reCaptcha instead of the captcha delivered with the LEPTON package, for example quickform, mpform and news (comment part).
For more information about Google reCaptcha please visit their documentation.
Usage is as simple as LEPTON itself:
Create a file recaptcha.php in the root of the module (mpform, etc) and enter your google codes in line 20 and 21:
const data_sitekey = "..."; // Enter your Google site-key const secrect_key = "..."; // Enter your Google secure-key
All settings etc had to be done in your google account.
You can download an example file recaptcha.php here.