Cloudflare, Inc. is an American web infrastructure and website security company that provides content delivery network services, DDoS mitigation, Internet security, and distributed domain name server services.[2] Cloudflare's services sit between a website's visitor and the Cloudflare user's hosting provider, acting as a reverse proxy for websites
OpenDNS is an American company providing Domain Name System (DNS) resolution services—with features such as phishing protection, optional content filtering, and DNS lookup in its DNS servers—and a cloud computing security product suite, Umbrella, designed to protect enterprise customers from malware, botnets, phishing, and targeted online attacks. The OpenDNS Global Network processes an estimated 100 billion DNS queries daily from 85 million users through 25 data centers worldwide
Quad9 is largest of the three global public recursive DNS resolvers which protect users from malware and phishing, and is notable for consistently being found to be by far the most effective (97%) at doing so in independent evaluations.[1][2][3] It was the first to use standards-based strong cryptography to protect the privacy of its users' communication, and the first to use DNSSEC cryptographic validation to protect users from domain name hijacking.[4][5][6][7] Quad9 is the only one of the three which protects users' privacy by not retaining or processing the IP address of its users, and is consequently also the only one which is GDPR-compliant