ProtonMail - Secure email with absolutely no compromises. Get your free encrypted email account today.
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.
Enigmail - Security extension to Mozilla Thunderbird and SeaMonkey
reCAPTCHA - reCAPTCHA is a free security service that protects your websites from spam and abuse.
Skizzle Email - Skizzle is the most secure way to share end-to-end encrypted files through email, backed by blockchain
GeeTest CAPTCHA - GeeTest protects your websites, mobile Apps and APIs from bot threats.