A purity score is rarely a plain average โ it's two steps: weighted aggregation, then a hard-signal floor. Step one sums each source's risk judgment by trust weight: a geo/ASN baseline, dedicated proxy-detection databases, abuse-report databases, and fraud-scoring services each contribute a different share, producing a continuous value. This separates "mildly suspicious" from "clearly dangerous."
But weighted averaging has a fatal flaw. If an IP hits one decisive signal โ say it's a known Tor exit node, or listed on an authoritative blocklist like Spamhaus โ while every other source stays quiet, the average can still land low and give a false sense of safety. So step two imposes a hard-signal floor: once such a decisive signal fires, the score is forced into the high-risk band regardless of what the other sources say. This is the litmus test for whether a purity tool is trustworthy โ a tool that only averages will miss genuinely dangerous IPs.
IPOK aggregates 8 risk sources โ ip-api, ipapi.is, proxycheck, AbuseIPDB, Scamalytics, StopForumSpam, IPQS โ plus a self-built IPOK-DB that folds in Tor exit lists, X4BNet's VPN/datacenter ranges, Spamhaus, and more. Showing sources side by side keeps it explainable: you can see whether proxycheck flagged a proxy, whether AbuseIPDB has reports on file, or whether it's simply a datacenter range โ instead of staring at a black-box number with no recourse.