The djblets.recaptcha module provides a form mixin that supports

reCAPTCHA API version 2.
reCAPTCHA is an implementation of CAPTCHA (Completely Automated

Public Turing Test to tell Computers and Humans Apart) by Google.

It is used in web forms to prevent them from being filled out and

submitted by automated bots.

Used this with Splat.
Ran unit tests.
Built and viewed the docs.