Why Free IP Blocklists Aren't Enough

Reaching for a free IP blocklist is a natural first move — it's free, it's a download, it feels like progress. But blocklists have structural limits that make them a weak foundation for fraud and abuse defense. Here's why, and what to do instead.

Problem 1: they go stale fast

IPs are constantly reassigned, proxies rotate, and VPN providers spin servers up and down. A list compiled last month already mislabels addresses — flagging IPs that are now clean and missing ones that just turned bad. Static data can't keep up with a dynamic problem.

Problem 2: they miss residential proxies entirely

This is the big one. Residential proxies use real ISP IPs that also serve legitimate customers. A blocklist literally cannot include them without blocking real users — so the most dangerous, evasion-focused traffic is exactly what blocklists omit. The FBI's warning about residential-proxy credential stuffing is a warning about traffic blocklists never see.

Problem 3: no confidence, no nuance

A blocklist is binary: in or out. There's no score, no proxy type, no way to treat "probably risky" differently from "certainly malicious." That forces blunt blocking, which causes false positives on shared and reassigned IPs — see why scoring beats blocking.

Problem 4: shared and reassigned IPs

Blocking a single IP can hit an entire household, office or carrier-grade NAT range full of legitimate users, because one bad actor was once on that address. Blocklists have no way to account for this.

What to use instead

Real-time, scored IP intelligence addresses every gap:

Use the proxy detection API for typed, scored verdicts, or roll signals into one IP fraud score.

Bottom line

Free IP blocklists go stale, miss residential proxies, and offer no confidence or nuance — forcing blunt blocks that hit real users. Real-time IP intelligence with typed, scored verdicts catches what blocklists miss and lets you score risk instead of blanket-blocking.