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.
reCAPTCHA - reCAPTCHA is a free security service that protects your websites from spam and abuse.
OOPSpam Anti-Spam API - The better, new standard to stop spam content.
UniqPin - UniqPin is a free for non-commercial use service which destiny improve ability of interfaces detect...
mosparo - the modern spam protection
StopForumSpam - StopForumSpam - a database of known forum and blog spam, its sources and the email addresses reported