Free; registration required by contacting Arbor
Free; optimized for Squid
Free; XML output available
CriticalStack Intel Marketplace
Free; registration required; optimized for Bro
Free tier available; registration required; query database via API
CYMRU Bogon List: Free
DShield Blocklist: Free
Free; combines several blacklists from other sources
Free; programmatic access; restrictions apply
Free; limited automation on request
Malc0de Database: Free
Free for non-commercial use
Malware Patrol’s Malware Block Lists
Free for non-commercial use
Commercial service; free licensing options may be available
Phishing sites; free for non-commercial use
Free; query database via API
Project Honey Pot’s Directory of Malicious IPs
Free; registration required to view more than 25 IPs
Scumware.org: Free
Shadowserver IP and URL Reports
Free; registration and approval required
Paid and free options available
Free; specific to VoIP abusers
ZeuS Tracker Blocklist and URLs: Free
www.BlockList.de: Free