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.
MailerLite - Affordable Email Marketing Software. Get all features (Segmentation, Automation, A/B testing) for up to 1,000 subscribers & send unlimited emails for free!
MTcaptcha - Enterprise Captcha solutions
Sendy - Sendy is a self hosted newsletter app that sends emails 100x cheaper via Amazon SES
GeeTest CAPTCHA - GeeTest protects your websites, mobile Apps and APIs from bot threats.
Publicate - Build Beautiful Emails. Export and Send Anywhere.