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.
Callblock - The first app to block telemarketers automatically in iOS
reCAPTCHA - reCAPTCHA is a free security service that protects your websites from spam and abuse.
Truecaller - Find a person by a name or phone number worldwide for free using Truecaller.
StopForumSpam - StopForumSpam - a database of known forum and blog spam, its sources and the email addresses reported
Hiya - Know who's calling or texting and block spammers on Android