- ATLAS from Arbor Networks: Free; registration required by contacting Arbor
- Blackweb Project: Free; optimized for Squid
- CLEAN-MX Realtime Database: Free; XML output available
- CriticalStack Intel Marketplace: Free; registration required; optimized for Bro
- Certly Guard: Free tier available; registration required; query database via API
- CYMRU Bogon List: Free
- DShield Blocklist: Free
- FireHOL IP Lists: Free; combines several blacklists from other sources
- Google Safe Browsing API: Free; programmatic access; restrictions apply
- hpHosts File: Free; limited automation on request
- Malc0de Database: Free
- Malware Domain Blocklist: Free for non-commercial use
- MalwareDomainList.com Hosts List: Free
- Malware Patrol’s Malware Block Lists: Free for non-commercial use
- MalwareURL List: Commercial service; free licensing options may be available
- OpenPhish: Phishing sites; free for non-commercial use
- PhishTank Phish Archive: 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
- Squidblacklist.org: Paid and free options available
- ZeuS Tracker Blocklist and URLs: Free
- www.BlockList.de: Free
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