Blocklists of Suspected Malicious IPs and URLs

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

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

Malware Domain Blocklist

Free for non-commercial use

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

Shadowserver IP and URL Reports

Free; registration and approval required

Squidblacklist.org

Paid and free options available

VoIP Blacklist

Free; specific to VoIP abusers