Is CleanBrowsing Effective? DNS Filtering Accuracy & Testing

How We Filter, How We Perform, and What Sets Us Apart

CleanBrowsing uses curated threat intelligence, machine learning categorization, and a global Anycast network to deliver accurate, low-latency DNS filtering. Learn how our technology works, how it performs in independent testing, and why organizations worldwide trust it to protect their networks.

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Step 1: How CleanBrowsing Filters Content

CleanBrowsing uses a combination of curated threat intelligence feeds, machine learning categorization (powered by Categorify), and community-driven recategorization to maintain accurate domain classifications. Our system processes over 355 billion DNS requests per month, continuously learning from real-world traffic patterns. Every domain is categorized into one or more of 21+ content categories, enabling granular filtering that goes beyond simple blocklists.

Unlike basic DNS blocklists that rely on static lists of known-bad domains, CleanBrowsing takes a multi-layered approach to categorization. When a new domain is first seen by our system, Categorify analyzes it using supervised machine learning models that consider domain registration age, content patterns, link relationships, and similarity to known categorized domains. This means newly created phishing sites and adult domains are often categorized within minutes of appearing on the internet, rather than waiting days or weeks for manual review.

Our categorization database is further enriched by multiple commercial and open-source threat intelligence feeds that track malware command-and-control servers, phishing campaigns, botnet infrastructure, and other malicious activity. These feeds are integrated in real-time, ensuring that our filtering reflects the current threat landscape. The result is a system that combines the speed of automation with the accuracy of human-curated intelligence.

Step 2: Independent Testing

CleanBrowsing has been evaluated by independent security researchers alongside other DNS filtering services including Quad9, OpenDNS, Norton ConnectSafe, ComodoSecure, and Yandex. In phishing protection tests, CleanBrowsing consistently performed at or near the top, demonstrating strong detection rates against newly registered malicious domains and known phishing infrastructure. Our continuous investment in categorization technology means coverage improves over time.

These independent evaluations matter because they test real-world effectiveness rather than theoretical capabilities. Researchers typically assemble fresh datasets of confirmed phishing URLs, malware distribution domains, and other threats, then query each DNS service to measure block rates. CleanBrowsing's strong showing in these tests reflects our investment in both automated detection (via Categorify) and manual curation by our security team.

It is worth noting that no DNS filtering service achieves 100% detection rates -- the threat landscape changes constantly, and new malicious domains appear every day. What matters is the combination of detection rate, false positive rate, and speed of categorization. CleanBrowsing optimizes across all three dimensions: high detection, minimal false positives, and rapid categorization of new threats. Users can also contribute to accuracy by submitting recategorization requests through our dashboard or via categorify.org.

Step 3: What CleanBrowsing Can (and Can't) Do

DNS filtering is highly effective at blocking entire domains associated with malware, phishing, adult content, gambling, and 21+ other categories. It works on every device that uses DNS -- no software installation required. This makes it one of the most versatile and easiest-to-deploy filtering technologies available.


What DNS Filtering Does Well

  • Domain-level blocking: Blocks access to entire domains categorized as malicious, adult, or otherwise unwanted. One DNS rule can block thousands of pages on a single domain.
  • Network-wide protection: Configure DNS once at the router and every device on the network is protected -- computers, phones, tablets, smart TVs, gaming consoles, and IoT devices.
  • Zero software overhead: No agents, browser extensions, or client software to install or maintain. DNS filtering works at the network layer.
  • Encrypted DNS support: CleanBrowsing supports DNS-over-HTTPS (DoH) and DNS-over-TLS (DoT) on every plan, including free filters, ensuring privacy and preventing DNS tampering.
  • Real-time updates: Newly categorized domains are blocked within minutes as our threat intelligence and categorization systems update continuously.

DNS Filtering Limitations

However, DNS filtering operates at the domain level. It cannot filter individual pages within a domain, block direct IP connections, or inspect encrypted traffic content. For example, DNS filtering can block all of a social media platform but cannot block a specific post or user profile within it. Similarly, if a user connects to a server by IP address rather than domain name, the DNS layer is bypassed entirely.

For these capabilities, DNS filtering should be complemented with firewall rules and device-level controls. We cover this topic in depth in our article on why DNS can't block keywords. The most effective content filtering strategies use DNS as the primary layer and add firewall rules, VPN blocking, and endpoint restrictions as additional layers of defense.

Step 4: Why Organizations Trust CleanBrowsing

CleanBrowsing is trusted by families, schools, libraries, and businesses worldwide because it combines effectiveness with simplicity. Our platform is designed to deliver enterprise-grade filtering without enterprise-grade complexity.


Key Reasons Organizations Choose CleanBrowsing

  • Global Anycast network: DNS queries are resolved at the nearest point of presence across 70+ data centers worldwide, ensuring low-latency resolution regardless of geographic location.
  • Encrypted DNS on every plan: DoH and DoT are available on all plans, including the free community filters. Privacy and security are not premium features -- they are baseline.
  • Transparent pricing: No per-user fees, no hidden costs, no stripped-down starter tiers designed to upsell. Paid plans include all features at a flat rate.
  • Free community filters: Three pre-configured filters (Family, Adult, and Security) are available to anyone with zero signup required. Just change your DNS and you are protected.
  • CIPA compliance support: Schools and libraries can use CleanBrowsing to meet Children's Internet Protection Act (CIPA) requirements with appropriate filtering and reporting.
  • Scalability: Whether you are protecting a home network or an enterprise with thousands of users, CleanBrowsing scales without complexity. The same technology powers individual families and large organizations.


The combination of accurate categorization, strong independent test results, transparent pricing, and global infrastructure makes CleanBrowsing an effective and trusted DNS filtering solution. To see it in action, try our free community filters -- no signup required.

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