Pingdom - With website monitoring from Pingdom you will be the first to know when your website is down. No installation required. 30-day free trial.
hCaptcha - Do you use a captcha to keep out bots? hCaptcha is a drop-in replacement for reCAPTCHA that earns website owners money and helps companies get their data labeled.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
reCAPTCHA - reCAPTCHA is a free security service that protects your websites from spam and abuse.
Better Uptime - We call you when your website goes down
AuthKong - A reliable captcha service, offers advanced security to protect websites from spam and abuse while ensuring a user-friendly experience for legitimate visitors.