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.
Algolia - Algolia's Search API makes it easy to deliver a great search experience in your apps & websites. Algolia Search provides hosted full-text, numerical, faceted and geolocalized search.
reCAPTCHA - reCAPTCHA is a free security service that protects your websites from spam and abuse.
Dynamic Yield - Personalization & customer experience management
GeeTest CAPTCHA - GeeTest protects your websites, mobile Apps and APIs from bot threats.
Optimizely - A/B testing you'll actually use.