Quad9 is a free DNS service that replaces your default ISP or enterprise DNS configuration. It blocks lookups of malicious host names from an up-to-the-minute list of threats, protecting against malware, phishing, spyware, and botnets. The service is operated by the Swiss-based Quad9 Foundation and handles 670M+ average daily blocks across 230+ resolver clusters in over 110 countries.

Quad9 prioritizes privacy: no data containing your IP address is ever logged, connections can be encrypted, and the platform is GDPR-compliant since 2017. The service is the only large DNS resolver with a founding charter that includes privacy as a primary goal.

Using threat intelligence from more than a dozen leading cybersecurity companies, Quad9 routes queries through a secure global network. If a site is known to be infected, access is automatically blocked. The mission is to improve Internet security and stability for everyone.

Quad9 is free, requires no sign-up, and collects no personal data. It can be configured on routers or devices, extending protection to IoT systems. As a not-for-profit, it relies on grants and partnerships, and usage helps prevent attacks like ransomware and bank account compromises.