Quad9

Quad9 is a global public recursive DNS resolver that aims to protect users from malware and phishing. Quad9 is operated by the Quad9 Foundation, a Swiss public-benefit, not-for-profit foundation with the purpose of improving the privacy and cybersecurity of Internet users, headquartered in Zürich. Quad9 is entirely subject to Swiss privacy law, and the Swiss government extends that protection of the law to Quad9's users throughout the world, regardless of citizenship or country of residence.

== Security and privacy == Several independent evaluations have found Quad9 to be the most effective (97%) at blocking malware and phishing domains. As of June, 2021, Quad9 was blocking more than 100 million malware infections and phishing attacks per day. Quad9's malware filtering is a user-selectable option. The domains which are filtered are not determined by Quad9, but instead supplied to Quad9 by a variety of independent threat-intelligence analysts, using different methodologies. Quad9 uses a reputation-scoring system to aggregate these sources, and removes "false positive" domains from the filter list, but does not itself add domains to the filter list.