Callwarden - Go to war on spam calls 📵
Callblock - The first app to block telemarketers automatically in iOS
unscan - Scanning of user-submitted content made simple.
Truecaller - Find a person by a name or phone number worldwide for free using Truecaller.
OOPSpam Anti-Spam API - The better, new standard to stop spam content.
Hiya - Know who's calling or texting and block spammers on Android