A Zapier step to validate a reCaptcha.

recaptcha.py

import requests

input_data['success'] = 'false'

captcha = input_data.get('captcha')
if captcha is None:
    return input_data

body = {
    'secret': 'SECRET',
    'response': captcha
}

r = requests.post("https://www.google.com/recaptcha/api/siteverify", params=body)
if r.ok:
    j = r.json()
    input_data['success'] = "true" if j.get('success', False) else "false"
    input_data['captcha-debug'] = j

return input_data