A number of Internet tools use DNSBLs (DNS blacklists) and retrieve them by HTTP/HTTPS. Here are a number of good resources for this.
www.reddit.com/r/PFSENSE/comments/7s3ug9/pfblockerng_recommended_lists/
forum.it-monkey.net/index.php?topic=17.0
supratim-sanyal.blogspot.com/2017/04/pfsense-pfblockerng-ultimate-list-of-ip.html